diff --git a/.gitignore b/.gitignore
index 894a44cc..799b90cf 100644
--- a/.gitignore
+++ b/.gitignore
@@ -102,3 +102,6 @@ venv.bak/
 
 # mypy
 .mypy_cache/
+
+# IDE
+.idea/
diff --git a/stellar_sdk/client/aiohttp_client.py b/stellar_sdk/client/aiohttp_client.py
index d14daebe..5a72a6d4 100644
--- a/stellar_sdk/client/aiohttp_client.py
+++ b/stellar_sdk/client/aiohttp_client.py
@@ -6,14 +6,13 @@
 import aiohttp
 from aiohttp_sse_client.client import EventSource
 
+from . import defines
 from .base_async_client import BaseAsyncClient
 from .response import Response
 from ..__version__ import __version__
 
 logger = logging.getLogger(__name__)
 
-# four ledgers sec, let's retry faster and not wait 60 secs.
-DEFAULT_REQUEST_TIMEOUT = 20
 DEFAULT_NUM_RETRIES = 3
 DEFAULT_BACKOFF_FACTOR = 0.5
 USER_AGENT = "py-stellar-sdk/%s/AiohttpClient" % __version__
@@ -30,7 +29,8 @@ class AiohttpClient(BaseAsyncClient):
     which represents the interface for making requests to a server instance.
 
     :param pool_size: persistent connection to Horizon and connection pool
-    :param request_timeout: the timeout for all requests
+    :param request_timeout: the timeout for all GET requests
+    :param post_timeout: the timeout for all POST requests
     :param backoff_factor: a backoff factor to apply between attempts after the second try
     :param user_agent: the server can use it to identify you
     """
@@ -38,13 +38,15 @@ class AiohttpClient(BaseAsyncClient):
     def __init__(
         self,
         pool_size: Optional[int] = None,
-        request_timeout: float = DEFAULT_REQUEST_TIMEOUT,
+        request_timeout: float = defines.DEFAULT_GET_TIMEOUT_SECONDS,
+        post_timeout: float = defines.DEFAULT_POST_TIMEOUT_SECONDS,
         backoff_factor: Optional[float] = DEFAULT_BACKOFF_FACTOR,
         user_agent: Optional[str] = None,
         **kwargs
     ) -> None:
         self.backoff_factor: Optional[float] = backoff_factor
         self.request_timeout: float = request_timeout
+        self.post_timeout: float = post_timeout
 
         # init session
         if pool_size is None:
@@ -99,7 +101,7 @@ async def post(self, url: str, data: Dict[str, str] = None) -> Response:
         :raise: :exc:`ConnectionError <stellar_sdk.exceptions.ConnectionError>`
         """
         try:
-            response = await self._session.post(url, data=data)
+            response = await self._session.post(url, data=data, timeout=aiohttp.ClientTimeout(total=self.post_timeout))
             return Response(
                 status_code=response.status,
                 text=await response.text(),
diff --git a/stellar_sdk/client/defines.py b/stellar_sdk/client/defines.py
new file mode 100644
index 00000000..ffa0fef0
--- /dev/null
+++ b/stellar_sdk/client/defines.py
@@ -0,0 +1,7 @@
+# Two ledgers average time + 1 sec
+DEFAULT_GET_TIMEOUT_SECONDS = 11
+
+# https://github.com/stellar/go/blob/7c4596db1ad107f770bd6e5a694ea5129440cb1e/services/horizon/internal/txsub/system.go#L314
+_HORIZON_SUBMIT_TRANSACTION_API_TIMEOUT_SECONDS = 30
+# POST is only used for submitting transactions to Horizon. Therefore we take the Horizon value with some grace.
+DEFAULT_POST_TIMEOUT_SECONDS = _HORIZON_SUBMIT_TRANSACTION_API_TIMEOUT_SECONDS * 1.1
diff --git a/stellar_sdk/client/requests_client.py b/stellar_sdk/client/requests_client.py
index b6f5f154..51991e2e 100644
--- a/stellar_sdk/client/requests_client.py
+++ b/stellar_sdk/client/requests_client.py
@@ -8,13 +8,12 @@
 from urllib3.exceptions import NewConnectionError
 from urllib3.util import Retry
 
+from . import defines
 from ..__version__ import __version__
 from ..client.base_sync_client import BaseSyncClient
 from ..client.response import Response
 from ..exceptions import ConnectionError
 
-# four ledgers sec, let's retry faster and not wait 60 secs.
-DEFAULT_REQUEST_TIMEOUT = 20
 DEFAULT_NUM_RETRIES = 3
 DEFAULT_BACKOFF_FACTOR = 0.5
 USER_AGENT = "py-stellar-sdk/%s/RequestsClient" % __version__
@@ -32,7 +31,8 @@ class RequestsClient(BaseSyncClient):
 
     :param pool_size: persistent connection to Horizon and connection pool
     :param num_retries: configurable request retry functionality
-    :param request_timeout: the timeout for all requests
+    :param request_timeout: the timeout for all GET requests
+    :param post_timeout: the timeout for all POST requests
     :param backoff_factor: a backoff factor to apply between attempts after the second try
     :param session: the request session
     :param stream_session: the stream request session
@@ -42,7 +42,8 @@ def __init__(
         self,
         pool_size: int = DEFAULT_POOLSIZE,
         num_retries: int = DEFAULT_NUM_RETRIES,
-        request_timeout: int = DEFAULT_REQUEST_TIMEOUT,
+        request_timeout: int = defines.DEFAULT_GET_TIMEOUT_SECONDS,
+        post_timeout: float = defines.DEFAULT_POST_TIMEOUT_SECONDS,
         backoff_factor: float = DEFAULT_BACKOFF_FACTOR,
         session: Session = None,
         stream_session: Session = None,
@@ -50,6 +51,7 @@ def __init__(
         self.pool_size: int = pool_size
         self.num_retries: int = num_retries
         self.request_timeout: int = request_timeout
+        self.post_timeout: float = post_timeout
         self.backoff_factor: float = backoff_factor
 
         # adding 504 to the tuple of statuses to retry
@@ -134,7 +136,7 @@ def post(self, url: str, data: Dict[str, str] = None) -> Response:
         :raise: :exc:`ConnectionError <stellar_sdk.exceptions.ConnectionError>`
         """
         try:
-            resp = self._session.post(url, data=data, timeout=self.request_timeout)
+            resp = self._session.post(url, data=data, timeout=self.post_timeout)
         except (RequestException, NewConnectionError) as err:
             raise ConnectionError(err)
         return Response(