diff --git a/session_redis/README.rst b/session_redis/README.rst
index 8a05b14..7a37e79 100644
--- a/session_redis/README.rst
+++ b/session_redis/README.rst
@@ -16,6 +16,8 @@ The storage of sessions in Redis is activated using environment variables.
 * ``ODOO_SESSION_REDIS_PREFIX`` is the prefix for the session keys (optional)
 * ``ODOO_SESSION_REDIS_EXPIRATION`` is the time in seconds before expiration of
   the sessions (default is 7 days)
+* ``ODOO_SESSION_REDIS_EXPIRATION_ANONYMOUS`` is the time in seconds before expiration of
+  the anonymous sessions (default is 3 hours)
 
 
 The keys are set to ``session:<session id>``.
diff --git a/session_redis/http.py b/session_redis/http.py
index f0279e5..783e463 100644
--- a/session_redis/http.py
+++ b/session_redis/http.py
@@ -42,6 +42,7 @@ port = int(os.environ.get('ODOO_SESSION_REDIS_PORT', 6379))
 prefix = os.environ.get('ODOO_SESSION_REDIS_PREFIX')
 password = os.environ.get('ODOO_SESSION_REDIS_PASSWORD')
 expiration = os.environ.get('ODOO_SESSION_REDIS_EXPIRATION')
+anon_expiration = os.environ.get('ODOO_SESSION_REDIS_EXPIRATION_ANONYMOUS')
 
 
 def session_store():
@@ -53,6 +54,7 @@ def session_store():
         redis_client = redis.Redis(host=host, port=port, password=password)
     return RedisSessionStore(redis=redis_client, prefix=prefix,
                              expiration=expiration,
+                             anon_expiration=anon_expiration,
                              session_class=Session)
 
 
diff --git a/session_redis/session.py b/session_redis/session.py
index 107820b..e2c659e 100644
--- a/session_redis/session.py
+++ b/session_redis/session.py
@@ -10,6 +10,7 @@ from werkzeug.contrib.sessions import SessionStore
 # this is equal to the duration of the session garbage collector in
 # openerp.http.session_gc()
 DEFAULT_SESSION_TIMEOUT = 60 * 60 * 24 * 7  # 7 days in seconds
+DEFAULT_SESSION_TIMEOUT_ANONYMOUS = 60 * 60 * 3  # 3 hours in seconds
 
 _logger = logging.getLogger(__name__)
 
@@ -18,13 +19,17 @@ class RedisSessionStore(SessionStore):
     """ SessionStore that saves session to redis """
 
     def __init__(self, redis, session_class=None,
-                 prefix='', expiration=None):
+                 prefix='', expiration=None, anon_expiration=None):
         super(RedisSessionStore, self).__init__(session_class=session_class)
         self.redis = redis
         if expiration is None:
             self.expiration = DEFAULT_SESSION_TIMEOUT
         else:
             self.expiration = expiration
+        if anon_expiration is None:
+            self.anon_expiration = DEFAULT_SESSION_TIMEOUT_ANONYMOUS
+        else:
+            self.anon_expiration = anon_expiration
         self.prefix = u'session:'
         if prefix:
             self.prefix = u'%s:%s:' % (
@@ -43,8 +48,15 @@ class RedisSessionStore(SessionStore):
         # That's why we need to look for the first item in it to get the
         # expiration parameter
         session_oe = session.itervalues().next()
-        expiration = getattr(session_oe, 'expiration', self.expiration)
 
+        # allow to set a custom expiration for a session
+        # such as a very short one for monitoring requests
+        if session._uid:
+            expiration = getattr(session_oe, 'expiration', self.expiration)
+        else:
+            expiration = getattr(
+                session_oe, 'expiration', self.anon_expiration
+            )
         if _logger.isEnabledFor(logging.DEBUG):
             _logger.debug("saving session with key '%s' and "
                           "expiration of %s seconds",