diff --git a/google-api-client/src/main/java/com/google/api/client/googleapis/auth/oauth2/CloudShellCredential.java b/google-api-client/src/main/java/com/google/api/client/googleapis/auth/oauth2/CloudShellCredential.java
index 9c6b3c665..692d210bc 100644
--- a/google-api-client/src/main/java/com/google/api/client/googleapis/auth/oauth2/CloudShellCredential.java
+++ b/google-api-client/src/main/java/com/google/api/client/googleapis/auth/oauth2/CloudShellCredential.java
@@ -46,7 +46,10 @@
  * OAuth2 credentials representing the built-in service account for Google Cloud Shell.
  *
  * @since 1.21.0
+ * @deprecated Please use <a href="https://github.com/googleapis/google-auth-library-java">
+ *   google-auth-library</a> for handling authentication and authorization from Cloud Shell.
  */
+@Deprecated
 public class CloudShellCredential extends GoogleCredential {
 
   private static final int ACCESS_TOKEN_INDEX = 2;
diff --git a/google-api-client/src/main/java/com/google/api/client/googleapis/auth/oauth2/GoogleCredential.java b/google-api-client/src/main/java/com/google/api/client/googleapis/auth/oauth2/GoogleCredential.java
index a92749bca..bebd47a74 100644
--- a/google-api-client/src/main/java/com/google/api/client/googleapis/auth/oauth2/GoogleCredential.java
+++ b/google-api-client/src/main/java/com/google/api/client/googleapis/auth/oauth2/GoogleCredential.java
@@ -164,7 +164,11 @@ public static GoogleCredential createCredentialForServiceAccountImpersonateUser(
  *
  * @since 1.7
  * @author Yaniv Inbar
+ * @deprecated Please use <a href="https://github.com/googleapis/google-auth-library-java">
+ *   google-auth-library</a> for handling Application Default Credentials and other non-OAuth2
+ *   based authentication.
  */
+@Deprecated
 public class GoogleCredential extends Credential {
 
   static final String USER_FILE_TYPE = "authorized_user";