diff --git a/Source/EntityFramework.Extended/Batch/SqlServerBatchRunner.cs b/Source/EntityFramework.Extended/Batch/SqlServerBatchRunner.cs
index 6f23996..66b04a8 100644
--- a/Source/EntityFramework.Extended/Batch/SqlServerBatchRunner.cs
+++ b/Source/EntityFramework.Extended/Batch/SqlServerBatchRunner.cs
@@ -1,8 +1,10 @@
 using System;
+using System.Collections.Generic;
 using System.Data;
 using System.Data.Common;
 using System.Data.Entity.Core.EntityClient;
 using System.Data.Entity.Core.Objects;
+using System.Diagnostics;
 using System.Linq;
 using System.Linq.Dynamic;
 using System.Linq.Expressions;
@@ -238,112 +240,38 @@ private int InternalUpdate<TEntity>(ObjectContext objectContext, EntityMap entit
                 bool wroteSet = false;
                 foreach (MemberBinding binding in memberInitExpression.Bindings)
                 {
-                    if (wroteSet)
-                        sqlBuilder.AppendLine(", ");
-
-                    string propertyName = binding.Member.Name;
-                    string columnName = entityMap.PropertyMaps
-                        .Where(p => p.PropertyName == propertyName)
-                        .Select(p => p.ColumnName)
-                        .FirstOrDefault();
-
-
-                    var memberAssignment = binding as MemberAssignment;
-                    if (memberAssignment == null)
-                        throw new ArgumentException("The update expression MemberBinding must only by type MemberAssignment.", "updateExpression");
-
-                    Expression memberExpression = memberAssignment.Expression;
-
-                    ParameterExpression parameterExpression = null;
-                    memberExpression.Visit((ParameterExpression p) =>
+                    var propertyMap = entityMap.PropertyMaps.Single(p => p.PropertyName == binding.Member.Name);
+                    
+                    var pm = propertyMap as PropertyMap;
+                    if (pm != null)
                     {
-                        if (p.Type == entityMap.EntityType)
-                            parameterExpression = p;
-
-                        return p;
-                    });
-
+                        AddUpdateRow<TEntity>(objectContext, entityMap, binding, sqlBuilder, updateCommand,
+                            entityMap.PropertyMaps, ref nameCount, ref wroteSet);
+                        continue;
+                    }
 
-                    if (parameterExpression == null)
+                    var cpm = propertyMap as ComplexPropertyMap;
+                    if (cpm != null)
                     {
-                        object value;
-
-                        if (memberExpression.NodeType == ExpressionType.Constant)
-                        {
-                            var constantExpression = memberExpression as ConstantExpression;
-                            if (constantExpression == null)
-                                throw new ArgumentException(
-                                    "The MemberAssignment expression is not a ConstantExpression.", "updateExpression");
-
-                            value = constantExpression.Value;
-                        }
-                        else
-                        {
-                            LambdaExpression lambda = Expression.Lambda(memberExpression, null);
-                            value = lambda.Compile().DynamicInvoke();
-                        }
-
-                        if (value != null)
-                        {
-                            string parameterName = "p__update__" + nameCount++;
-                            var parameter = updateCommand.CreateParameter();
-                            parameter.ParameterName = parameterName;
-                            parameter.Value = value;
-                            updateCommand.Parameters.Add(parameter);
-
-                            sqlBuilder.AppendFormat("[{0}] = @{1}", columnName, parameterName);
-                        }
-                        else
+                        var memberAssignment = binding as MemberAssignment;
+                        if (memberAssignment == null)
+                            throw new ArgumentException(
+                                "The update expression MemberBinding must only by type MemberAssignment.",
+                                "updateExpression");
+                        var expr = memberAssignment.Expression as MemberInitExpression;
+                        if (expr == null)
+                            throw new ArgumentException(
+                                "The update expression MemberBinding must only by type MemberAssignment.",
+                                "updateExpression");
+                        foreach (var subBinding in expr.Bindings)
                         {
-                            sqlBuilder.AppendFormat("[{0}] = NULL", columnName);
+                            AddUpdateRow<TEntity>(objectContext, entityMap, subBinding, sqlBuilder, updateCommand,
+                                cpm.Elements, ref nameCount, ref wroteSet);
                         }
+                        continue;
                     }
-                    else
-                    {
-                        // create clean objectset to build query from
-                        var objectSet = objectContext.CreateObjectSet<TEntity>();
-
-                        Type[] typeArguments = new[] { entityMap.EntityType, memberExpression.Type };
-
-                        ConstantExpression constantExpression = Expression.Constant(objectSet);
-                        LambdaExpression lambdaExpression = Expression.Lambda(memberExpression, parameterExpression);
-
-                        MethodCallExpression selectExpression = Expression.Call(
-                            typeof(Queryable),
-                            "Select",
-                            typeArguments,
-                            constantExpression,
-                            lambdaExpression);
-
-                        // create query from expression
-                        var selectQuery = objectSet.CreateQuery(selectExpression, entityMap.EntityType);
-                        string sql = selectQuery.ToTraceString();
-
-                        // parse select part of sql to use as update
-                        string regex = @"SELECT\s*\r\n\s*(?<ColumnValue>.+)?\s*AS\s*(?<ColumnAlias>\[\w+\])\r\n\s*FROM\s*(?<TableName>\[\w+\]\.\[\w+\]|\[\w+\])\s*AS\s*(?<TableAlias>\[\w+\])";
-                        Match match = Regex.Match(sql, regex);
-                        if (!match.Success)
-                            throw new ArgumentException("The MemberAssignment expression could not be processed.", "updateExpression");
-
-                        string value = match.Groups["ColumnValue"].Value;
-                        string alias = match.Groups["TableAlias"].Value;
-
-                        value = value.Replace(alias + ".", "");
 
-                        foreach (ObjectParameter objectParameter in selectQuery.Parameters)
-                        {
-                            string parameterName = "p__update__" + nameCount++;
-
-                            var parameter = updateCommand.CreateParameter();
-                            parameter.ParameterName = parameterName;
-                            parameter.Value = objectParameter.Value ?? DBNull.Value;
-                            updateCommand.Parameters.Add(parameter);
-
-                            value = value.Replace(objectParameter.Name, parameterName);
-                        }
-                        sqlBuilder.AppendFormat("[{0}] = {1}", columnName, value);
-                    }
-                    wroteSet = true;
+                    throw new InvalidOperationException(string.Format("Invalid propertyMap type: {0}", propertyMap.GetType()));
                 }
 
                 sqlBuilder.AppendLine(" ");
@@ -372,6 +300,7 @@ private int InternalUpdate<TEntity>(ObjectContext objectContext, EntityMap entit
 #else
                 int result = updateCommand.ExecuteNonQuery();
 #endif
+
                 // only commit if created transaction
                 if (ownTransaction)
                     updateTransaction.Commit();
@@ -389,6 +318,115 @@ private int InternalUpdate<TEntity>(ObjectContext objectContext, EntityMap entit
             }
         }
 
+        private static void AddUpdateRow<TEntity>(ObjectContext objectContext, EntityMap entityMap, MemberBinding binding, StringBuilder sqlBuilder, DbCommand updateCommand, IEnumerable<IPropertyMapElement> propertyMap, ref int nameCount, ref bool wroteSet)
+            where TEntity : class
+        {
+            if (wroteSet)
+                sqlBuilder.AppendLine(", ");
+
+            string propertyName = binding.Member.Name;
+            var property =
+                propertyMap.SingleOrDefault(p => p.PropertyName == propertyName) as PropertyMap;
+            Debug.Assert(property != null, "property != null");
+            string columnName = property.ColumnName;
+            var memberAssignment = binding as MemberAssignment;
+            if (memberAssignment == null)
+                throw new ArgumentException("The update expression MemberBinding must only by type MemberAssignment.", "binding");
+
+            Expression memberExpression = memberAssignment.Expression;
+
+            ParameterExpression parameterExpression = null;
+            memberExpression.Visit((ParameterExpression p) =>
+            {
+                if (p.Type == entityMap.EntityType)
+                    parameterExpression = p;
+
+                return p;
+            });
+
+
+            if (parameterExpression == null)
+            {
+                object value;
+
+                if (memberExpression.NodeType == ExpressionType.Constant)
+                {
+                    var constantExpression = memberExpression as ConstantExpression;
+                    if (constantExpression == null)
+                        throw new ArgumentException(
+                            "The MemberAssignment expression is not a ConstantExpression.", "binding");
+
+                    value = constantExpression.Value;
+                }
+                else
+                {
+                    LambdaExpression lambda = Expression.Lambda(memberExpression, null);
+                    value = lambda.Compile().DynamicInvoke();
+                }
+
+                if (value != null)
+                {
+                    string parameterName = "p__update__" + nameCount++;
+                    var parameter = updateCommand.CreateParameter();
+                    parameter.ParameterName = parameterName;
+                    parameter.Value = value;
+                    updateCommand.Parameters.Add(parameter);
+
+                    sqlBuilder.AppendFormat("[{0}] = @{1}", columnName, parameterName);
+                }
+                else
+                {
+                    sqlBuilder.AppendFormat("[{0}] = NULL", columnName);
+                }
+            }
+            else
+            {
+                // create clean objectset to build query from
+                var objectSet = objectContext.CreateObjectSet<TEntity>();
+
+                Type[] typeArguments = new[] { entityMap.EntityType, memberExpression.Type };
+
+                ConstantExpression constantExpression = Expression.Constant(objectSet);
+                LambdaExpression lambdaExpression = Expression.Lambda(memberExpression, parameterExpression);
+
+                MethodCallExpression selectExpression = Expression.Call(
+                    typeof(Queryable),
+                    "Select",
+                    typeArguments,
+                    constantExpression,
+                    lambdaExpression);
+
+                // create query from expression
+                var selectQuery = objectSet.CreateQuery(selectExpression, entityMap.EntityType);
+                string sql = selectQuery.ToTraceString();
+
+                // parse select part of sql to use as update
+                string regex = @"SELECT\s*\r\n\s*(?<ColumnValue>.+)?\s*AS\s*(?<ColumnAlias>\[\w+\])\r\n\s*FROM\s*(?<TableName>\[\w+\]\.\[\w+\]|\[\w+\])\s*AS\s*(?<TableAlias>\[\w+\])";
+                Match match = Regex.Match(sql, regex);
+                if (!match.Success)
+                    throw new ArgumentException("The MemberAssignment expression could not be processed.", "binding");
+
+                string value = match.Groups["ColumnValue"].Value;
+                string alias = match.Groups["TableAlias"].Value;
+
+                value = value.Replace(alias + ".", "");
+
+                foreach (ObjectParameter objectParameter in selectQuery.Parameters)
+                {
+                    string parameterName = "p__update__" + nameCount++;
+
+                    var parameter = updateCommand.CreateParameter();
+                    parameter.ParameterName = parameterName;
+                    parameter.Value = objectParameter.Value ?? DBNull.Value;
+                    updateCommand.Parameters.Add(parameter);
+
+                    value = value.Replace(objectParameter.Name, parameterName);
+                }
+                sqlBuilder.AppendFormat("[{0}] = {1}", columnName, value);
+            }
+            wroteSet = true;
+        }
+
         private static Tuple<DbConnection, DbTransaction> GetStore(ObjectContext objectContext)
         {
             // TODO, re-eval if this is needed
diff --git a/Source/EntityFramework.Extended/EntityFramework.Extended.csproj b/Source/EntityFramework.Extended/EntityFramework.Extended.csproj
index c595f28..b58d62f 100644
--- a/Source/EntityFramework.Extended/EntityFramework.Extended.csproj
+++ b/Source/EntityFramework.Extended/EntityFramework.Extended.csproj
@@ -104,10 +104,12 @@
     <Compile Include="Extensions\BatchExtensions.cs" />
     <Compile Include="Extensions\ObjectContextExtensions.cs" />
     <Compile Include="IContainer.cs" />
+    <Compile Include="Mapping\ComplexPropertyMap.cs" />
     <Compile Include="Mapping\EntityMap.cs" />
     <Compile Include="Extensions\ExpressionExtensions.cs" />
     <Compile Include="Extensions\ObjectQueryExtensions.cs" />
     <Compile Include="Mapping\IMappingProvider.cs" />
+    <Compile Include="Mapping\IPropertyMapElement.cs" />
     <Compile Include="Mapping\MetadataMappingProvider.cs" />
     <Compile Include="Mapping\MappingResolver.cs" />
     <Compile Include="Mapping\PropertyMap.cs" />
diff --git a/Source/EntityFramework.Extended/EntityFramework.Extended.net40.csproj b/Source/EntityFramework.Extended/EntityFramework.Extended.net40.csproj
index 88fb4e5..c8bd367 100644
--- a/Source/EntityFramework.Extended/EntityFramework.Extended.net40.csproj
+++ b/Source/EntityFramework.Extended/EntityFramework.Extended.net40.csproj
@@ -104,10 +104,12 @@
     <Compile Include="Extensions\BatchExtensions.cs" />
     <Compile Include="Extensions\ObjectContextExtensions.cs" />
     <Compile Include="IContainer.cs" />
+    <Compile Include="Mapping\ComplexPropertyMap.cs" />
     <Compile Include="Mapping\EntityMap.cs" />
     <Compile Include="Extensions\ExpressionExtensions.cs" />
     <Compile Include="Extensions\ObjectQueryExtensions.cs" />
     <Compile Include="Mapping\IMappingProvider.cs" />
+    <Compile Include="Mapping\IPropertyMapElement.cs" />
     <Compile Include="Mapping\MetadataMappingProvider.cs" />
     <Compile Include="Mapping\MappingResolver.cs" />
     <Compile Include="Mapping\PropertyMap.cs" />
@@ -159,4 +161,4 @@
   <Target Name="AfterBuild">
   </Target>
   -->
-</Project>
\ No newline at end of file
+</Project>
diff --git a/Source/EntityFramework.Extended/Mapping/ComplexPropertyMap.cs b/Source/EntityFramework.Extended/Mapping/ComplexPropertyMap.cs
new file mode 100644
index 0000000..776e8ee
--- /dev/null
+++ b/Source/EntityFramework.Extended/Mapping/ComplexPropertyMap.cs
@@ -0,0 +1,37 @@
+using System.Collections.Generic;
+using System.Linq;
+
+namespace EntityFramework.Mapping
+{
+    /// <summary>
+    /// A property map element representing a complex class
+    /// </summary>
+    public class ComplexPropertyMap : IPropertyMapElement
+    {
+        private readonly IList<IPropertyMapElement> _elements;
+
+        /// <summary>
+        /// Create a new instance.
+        /// </summary>
+        /// <param name="propertyName">the property name.</param>
+        /// <param name="elements">the mapped elements of the complex property</param>
+        public ComplexPropertyMap(string propertyName, IEnumerable<IPropertyMapElement> elements)
+        {
+            _elements = elements.ToList();
+            PropertyName = propertyName;
+        }
+
+        /// <summary>
+        /// The property name.
+        /// </summary>
+        public string PropertyName { get; private set; }
+
+        /// <summary>
+        /// The complex type's elements.
+        /// </summary>
+        public IEnumerable<IPropertyMapElement> Elements
+        {
+            get { return _elements; }
+        }
+    }
+}
diff --git a/Source/EntityFramework.Extended/Mapping/EntityMap.cs b/Source/EntityFramework.Extended/Mapping/EntityMap.cs
index c338452..2e84b5b 100644
--- a/Source/EntityFramework.Extended/Mapping/EntityMap.cs
+++ b/Source/EntityFramework.Extended/Mapping/EntityMap.cs
@@ -20,7 +20,7 @@ public EntityMap(Type entityType)
         {
             _entityType = entityType;
             _keyMaps = new List<PropertyMap>();
-            _propertyMaps = new List<PropertyMap>();
+            _propertyMaps = new List<IPropertyMapElement>();
         }
 
         /// <summary>
@@ -57,11 +57,11 @@ public Type EntityType
         /// </value>
         public string TableName { get; set; }
 
-        private readonly List<PropertyMap> _propertyMaps;
+        private readonly List<IPropertyMapElement> _propertyMaps;
         /// <summary>
         /// Gets the property maps.
         /// </summary>
-        public List<PropertyMap> PropertyMaps
+        public List<IPropertyMapElement> PropertyMaps
         {
             get { return _propertyMaps; }
         }
diff --git a/Source/EntityFramework.Extended/Mapping/IPropertyMapElement.cs b/Source/EntityFramework.Extended/Mapping/IPropertyMapElement.cs
new file mode 100644
index 0000000..5139d9a
--- /dev/null
+++ b/Source/EntityFramework.Extended/Mapping/IPropertyMapElement.cs
@@ -0,0 +1,13 @@
+namespace EntityFramework.Mapping
+{
+    /// <summary>
+    /// Interface representing a property map element which can be single or complex.
+    /// </summary>
+    public interface IPropertyMapElement
+    {
+        /// <summary>
+        /// Gets or sets the name of the property.
+        /// </summary>
+        string PropertyName { get; }
+    }
+}
diff --git a/Source/EntityFramework.Extended/Mapping/MetadataMappingProvider.cs b/Source/EntityFramework.Extended/Mapping/MetadataMappingProvider.cs
index 2465e2f..edee697 100644
--- a/Source/EntityFramework.Extended/Mapping/MetadataMappingProvider.cs
+++ b/Source/EntityFramework.Extended/Mapping/MetadataMappingProvider.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Data.Entity;
 using System.Data.Entity.Core.Mapping;
 using System.Data.Entity.Core.Metadata.Edm;
@@ -92,14 +93,14 @@ private static void SetKeys(EntityMap entityMap)
             {
                 var property = entityMap.PropertyMaps.FirstOrDefault(p => p.PropertyName == edmMember.Name);
                 if (property == null)
-                    continue;
-
-                var map = new PropertyMap
-                {
-                    PropertyName = property.PropertyName,
-                    ColumnName = property.ColumnName
-                };
-                entityMap.KeyMaps.Add(map);
+                    throw new InvalidOperationException(string.Format("There is no mapping for key member '{0}'.", edmMember));
+
+                var propertyMap = property as PropertyMap;
+                if (propertyMap == null)
+                    throw new InvalidOperationException(string.Format("KeyMember {1} of entity {0} cannot be complex.",
+                        entityMap.TableName, edmMember.Name));
+
+                entityMap.KeyMaps.Add(propertyMap);
             }
         }
 
@@ -107,23 +108,33 @@ private static void SetProperties(EntityMap entityMap, MappingFragment mappingFr
         {
             foreach (var propertyMapping in mappingFragment.PropertyMappings)
             {
-                var map = new PropertyMap();
-                map.PropertyName = propertyMapping.Property.Name;
-
+                var map = CreatePropertyMap(propertyMapping);
                 entityMap.PropertyMaps.Add(map);
+            }
+        }
+
+        private static IPropertyMapElement CreatePropertyMap(PropertyMapping propertyMapping)
+        {
+            var scalarPropertyMapping = propertyMapping as ScalarPropertyMapping;
+            if (scalarPropertyMapping != null)
+            {
+                return new PropertyMap(propertyMapping.Property.Name, scalarPropertyMapping.Column.Name);
+            }
 
-                var scalarPropertyMapping = propertyMapping as ScalarPropertyMapping;
-                if (scalarPropertyMapping != null)
-                {
-                    map.ColumnName = scalarPropertyMapping.Column.Name;
-                    continue;
-                }
+            var complexPropertyMapping = propertyMapping as ComplexPropertyMapping;
+            if (complexPropertyMapping != null)
+            {
+                var typeElements = 
+                    from typeMapping in complexPropertyMapping.TypeMappings 
+                    from property in typeMapping.PropertyMappings 
+                    select CreatePropertyMap(property);
 
-                // TODO support complex mapping
-                var complexPropertyMapping = propertyMapping as ComplexPropertyMapping;
+                return new ComplexPropertyMap(propertyMapping.Property.Name, typeElements.ToList());
             }
+
+            throw new InvalidOperationException("Invalid or unknown propertyMapping type: " + propertyMapping.GetType());
         }
-        
+
         private static void SetTableName(EntityMap entityMap)
         {
             var builder = new StringBuilder(50);
diff --git a/Source/EntityFramework.Extended/Mapping/PropertyMap.cs b/Source/EntityFramework.Extended/Mapping/PropertyMap.cs
index abe0d78..004ec0d 100644
--- a/Source/EntityFramework.Extended/Mapping/PropertyMap.cs
+++ b/Source/EntityFramework.Extended/Mapping/PropertyMap.cs
@@ -6,15 +6,27 @@ namespace EntityFramework.Mapping
     /// A class representing a property map
     /// </summary>
     [DebuggerDisplay("Property: {PropertyName}, Column: {ColumnName}")]
-    public class PropertyMap
+    public class PropertyMap : IPropertyMapElement
     {
+        /// <summary>
+        /// Create a new instance.
+        /// </summary>
+        /// <param name="propertyName">the property name</param>
+        /// <param name="columnName">the column name</param>
+        public PropertyMap(string propertyName, string columnName)
+        {
+            ColumnName = columnName;
+            PropertyName = propertyName;
+        }
+
         /// <summary>
         /// Gets or sets the name of the property.
         /// </summary>
-        public string PropertyName { get; set; }
+        public string PropertyName { get; private set; }
+
         /// <summary>
         /// Gets or sets the name of the column.
         /// </summary>
-        public string ColumnName { get; set; }
+        public string ColumnName { get; private set; }
     }
 }
\ No newline at end of file