diff --git a/Yavsc/Helpers/GoogleHelpers.cs b/Yavsc/Helpers/GoogleHelpers.cs
index d1d8f56f..54aad5ea 100644
--- a/Yavsc/Helpers/GoogleHelpers.cs
+++ b/Yavsc/Helpers/GoogleHelpers.cs
@@ -39,6 +39,8 @@ namespace Yavsc.Helpers
     using Google.Apis.Auth.OAuth2.Flows;
     using Google.Apis.Util.Store;
     using Google.Apis.Auth.OAuth2.Responses;
+    using Google.Apis.Util;
+
 
 
 
@@ -125,6 +127,11 @@ namespace Yavsc.Helpers
                throw new InvalidOperationException("No Google login");
             var flow = new GoogleAuthorizationCodeFlow(new GoogleAuthorizationCodeFlow.Initializer());
             var token = await store.GetAsync<TokenResponse>(googleUserLoginKey);
+            // token != null
+            var c = SystemClock.Default;
+            if (token.IsExpired(c)) {
+                token = await RefreshToken(token);
+            }
             return new UserCredential(flow, googleUserLoginKey, token);
         }
         public static async Task<Period[]> GetFreeTime (this ICalendarManager manager, string calId, DateTime startDate, DateTime endDate) 
diff --git a/Yavsc/Services/GoogleApis/CalendarManager.cs b/Yavsc/Services/GoogleApis/CalendarManager.cs
index 9c6ff9bd..ef9fbaab 100644
--- a/Yavsc/Services/GoogleApis/CalendarManager.cs
+++ b/Yavsc/Services/GoogleApis/CalendarManager.cs
@@ -36,6 +36,8 @@ namespace Yavsc.Services
 {
     using System.Threading;
     using Google.Apis.Auth.OAuth2.Flows;
+    using Google.Apis.Auth.OAuth2.Responses;
+    using Google.Apis.Util;
     using Yavsc.Helpers;
     using Yavsc.Models;
     using Yavsc.Models.Calendar;
@@ -240,6 +242,10 @@ namespace Yavsc.Services
             var login = await _dbContext.GetGoogleUserLoginAsync(userId);
             if (login == null) return null;
             var token = await _flow.LoadTokenAsync(login.ProviderKey, CancellationToken.None);
+            var c = SystemClock.Default;
+            if (token.IsExpired(c)) {
+                token = await RefreshToken(token);
+            }
             UserCredential cred = new UserCredential(_flow,login.ProviderKey,token);
 			return  new CalendarService(new BaseClientService.Initializer()
             {
@@ -247,5 +253,23 @@ namespace Yavsc.Services
                 ApplicationName = "Yavsc"
             });
 		}
+
+        public static async Task<TokenResponse> RefreshToken(TokenResponse oldResponse)
+        {
+            string ep = " https://www.googleapis.com/oauth2/v4/token";
+            // refresh_token client_id client_secret grant_type=refresh_token
+            try {
+                using (var m = new SimpleJsonPostMethod(ep)) {
+                    return await m.Invoke<TokenResponse>(
+                        new { refresh_token= oldResponse.RefreshToken, client_id=Startup.GoogleSettings.ClientId,
+                         client_secret=Startup.GoogleSettings.ClientSecret,
+                          grant_type="refresh_token" }
+                    );
+                }
+            }
+            catch (Exception ex) {
+                throw new Exception ("Quelque chose s'est mal passé à l'envoi",ex);
+            }
+        }
     }
 }