diff --git a/.gitignore b/.gitignore
index 21e397b..fa1d0dc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,3 +9,4 @@ dist/
 src/
 .venv
 .idea
+docs/_build/
diff --git a/docs/sections/settings.rst b/docs/sections/settings.rst
index f8fcbc9..f3e4329 100644
--- a/docs/sections/settings.rst
+++ b/docs/sections/settings.rst
@@ -96,7 +96,16 @@ OIDC_IDTOKEN_PROCESSING_HOOK
 ============================
 
 OPTIONAL. ``str``. A string with the location of your function hook.
-here you can add extra dictionary values specific for your app into id_token.
+Here you can add extra dictionary values specific for your app into id_token.
+
+The function receives a ``id_token`` dictionary and ``user`` instance 
+and returns it with additional fields.
+
+Default is::
+
+    def default_idtoken_processing_hook(id_token, user):
+
+        return id_token
 
 OIDC_IDTOKEN_SUB_GENERATOR
 ==========================
diff --git a/oidc_provider/lib/utils/common.py b/oidc_provider/lib/utils/common.py
index 8eb0869..9d37f4f 100644
--- a/oidc_provider/lib/utils/common.py
+++ b/oidc_provider/lib/utils/common.py
@@ -55,8 +55,10 @@ def default_idtoken_processing_hook(id_token, user):
 
     :param id_token: dictionary contains values that going to be serialized into `id_token`
     :type id_token: dict
+
     :param user: user for whom id_token is generated
     :type user: User
+
     :return: custom modified dictionary of values for `id_token`
     :rtype dict
     """
diff --git a/oidc_provider/tests/app/utils.py b/oidc_provider/tests/app/utils.py
index a644298..9b76233 100644
--- a/oidc_provider/tests/app/utils.py
+++ b/oidc_provider/tests/app/utils.py
@@ -108,9 +108,10 @@ def fake_sub_generator(user):
     return user.email
 
 
-def fake_idtoken_processing_hook(id_token):
+def fake_idtoken_processing_hook(id_token, user):
     """
     Fake function for inserting some keys into token. Testing OIDC_IDTOKEN_PROCESSING_HOOK.
     """
     id_token['test_idtoken_processing_hook'] = FAKE_RANDOM_STRING
+    id_token['test_idtoken_processing_hook_user_email'] = user.email
     return id_token
diff --git a/oidc_provider/tests/test_token_endpoint.py b/oidc_provider/tests/test_token_endpoint.py
index e67b3ba..bb9e772 100644
--- a/oidc_provider/tests/test_token_endpoint.py
+++ b/oidc_provider/tests/test_token_endpoint.py
@@ -352,3 +352,4 @@ class TokenTestCase(TestCase):
         id_token = JWT().unpack(response_dic['id_token'].encode('utf-8')).payload()
 
         self.assertEqual(id_token.get('test_idtoken_processing_hook'), FAKE_RANDOM_STRING)
+        self.assertEqual(id_token.get('test_idtoken_processing_hook_user_email'), self.user.email)