diff --git a/lib/google/api_client/auth/installed_app.rb b/lib/google/api_client/auth/installed_app.rb
index 150099e34..2980ed6e0 100644
--- a/lib/google/api_client/auth/installed_app.rb
+++ b/lib/google/api_client/auth/installed_app.rb
@@ -33,6 +33,7 @@ module Google
     #    drive = Drive::DriveService.new
     #    drive.authorization = authorization
     #
+    # @deprecated Use google-auth-library-ruby instead
     class InstalledAppFlow
 
       RESPONSE_BODY = <<-HTML
diff --git a/lib/google/api_client/auth/key_utils.rb b/lib/google/api_client/auth/key_utils.rb
index 6b6e0cfe5..28510487c 100644
--- a/lib/google/api_client/auth/key_utils.rb
+++ b/lib/google/api_client/auth/key_utils.rb
@@ -18,6 +18,7 @@ module Google
     # Helper for loading keys from the PKCS12 files downloaded when
     # setting up service accounts at the APIs Console.
     #
+    # @deprecated Use google-auth-library-ruby instead
     module KeyUtils
       ##
       # Loads a key from PKCS12 file, assuming a single private key
diff --git a/lib/google/api_client/auth/storage.rb b/lib/google/api_client/auth/storage.rb
index e5a305231..dd74e7f7b 100644
--- a/lib/google/api_client/auth/storage.rb
+++ b/lib/google/api_client/auth/storage.rb
@@ -21,6 +21,7 @@ module Google
     # JSON serialized file. Meant to resemble the serialized format
     # http://google-api-python-client.googlecode.com/hg/docs/epy/oauth2client.file.Storage-class.html
     #
+    # @deprecated Use google-auth-library-ruby instead
     class Storage
 
       AUTHORIZATION_URI = 'https://accounts.google.com/o/oauth2/auth'
diff --git a/lib/google/api_client/auth/storages/file_store.rb b/lib/google/api_client/auth/storages/file_store.rb
index b66118a13..a82457c96 100644
--- a/lib/google/api_client/auth/storages/file_store.rb
+++ b/lib/google/api_client/auth/storages/file_store.rb
@@ -21,6 +21,7 @@ module Google
     # JSON serialized file. Meant to resemble the serialized format
     # http://google-api-python-client.googlecode.com/hg/docs/epy/oauth2client.file.Storage-class.html
     #
+    # @deprecated Use google-auth-library-ruby instead
     class FileStore
 
       attr_accessor :path
diff --git a/lib/google/api_client/auth/storages/redis_store.rb b/lib/google/api_client/auth/storages/redis_store.rb
index 341b8f910..d283438b7 100644
--- a/lib/google/api_client/auth/storages/redis_store.rb
+++ b/lib/google/api_client/auth/storages/redis_store.rb
@@ -16,6 +16,7 @@ require 'json'
 
 module Google
   class APIClient
+    # @deprecated Use google-auth-library-ruby instead
     class RedisStore
 
       DEFAULT_REDIS_CREDENTIALS_KEY = "google_api_credentials"
diff --git a/lib/google/api_client/client_secrets.rb b/lib/google/api_client/client_secrets.rb
index fcf2bf8c4..5bb195393 100644
--- a/lib/google/api_client/client_secrets.rb
+++ b/lib/google/api_client/client_secrets.rb
@@ -23,7 +23,7 @@ module Google
     # inspired by the Google API Python client.
     #
     # @see https://developers.google.com/api-client-library/python/guide/aaa_client_secrets
-    #
+    # @deprecated Use google-auth-library-ruby instead
     # @example
     #   {
     #     "web": {
@@ -121,7 +121,7 @@ module Google
       def to_json
         return MultiJson.dump(to_hash)
       end
-      
+
       def to_hash
         {
           self.flow => ({
@@ -146,7 +146,7 @@ module Google
           end
         }
       end
-      
+
       def to_authorization
         gem 'signet', '>= 0.4.0'
         require 'signet/oauth_2/client'