diff --git a/NEWS b/NEWS
index 739f10c8b..5fba47add 100644
--- a/NEWS
+++ b/NEWS
@@ -4,6 +4,7 @@
 Enhancements
  - [web] prohibit subscribing a user with no rights
  - [web] new button to mark a task as completed (#4531)
+ - [web] new button to reset Calendar categories to defaults
 
 Bug fixes
  - [web] include mail account name in form validation (#4532)
diff --git a/SoObjects/SOGo/SOGoDefaults.plist b/SoObjects/SOGo/SOGoDefaults.plist
index 605d0f554..980000489 100644
--- a/SoObjects/SOGo/SOGoDefaults.plist
+++ b/SoObjects/SOGo/SOGoDefaults.plist
@@ -159,28 +159,28 @@
     );
 
     SOGoCalendarCategoriesColors = {
-        "Customer" = "#CCCCCC";
-        "Calls" = "#FFCC33";
-        "Favorites" = "#CCCCCC";
-        "Meeting" = "#CCCCCC";
-        "Ideas" = "#CCCCCC";
-        "Miscellaneous" = "#CCCCCC";
-        "Birthday" = "#CCCCCC";
-        "Anniversary" = "#CCCCCC";
-        "Vacation" = "#CCCCCC";
-        "Travel" = "#CCCCCC";
-        "Projects" = "#CCCCCC";
-        "Suppliers" = "#CCCCCC";
-        "Gifts" = "#CCCCCC";
-        "Clients" = "#CCCCCC";
-        "Issues" = "#CCCCCC";
-        "Business" = "#CCCCCC";
-        "Holidays" = "#CCCCCC";
-        "Personal" = "#CCCCCC";
-        "Status" = "#CCCCCC";
-        "Competition" = "#CCCCCC";
-        "Follow up" = "#CCCCCC";
-        "Public Holiday" = "#CCCCCC";
+        "Customer" = "#F8D800";
+        "Calls" = "#0396FF";
+        "Favorites" = "#EA5455";
+        "Meeting" = "#7367F0";
+        "Ideas" = "#32CCBC";
+        "Miscellaneous" = "#F6416C";
+        "Birthday" = "#28C76F";
+        "Anniversary" = "#9F44D3";
+        "Vacation" = "#623AA2";
+        "Travel" = "#F55555";
+        "Projects" = "#8C1BAB";
+        "Suppliers" = "#9708CC";
+        "Gifts" = "#736EFE";
+        "Clients" = "#E96D71";
+        "Issues" = "#3677FF";
+        "Business" = "#FA016D";
+        "Holidays" = "#0E197D";
+        "Personal" = "#DE4313";
+        "Status" = "#002661";
+        "Competition" = "#6018DC";
+        "Follow up" = "#D939CD";
+        "Public Holiday" = "#E80505";
     };
 
     SOGoSubscriptionFolderFormat = "%{FolderName} (%{UserName} <%{Email}>)";
diff --git a/UI/PreferencesUI/English.lproj/Localizable.strings b/UI/PreferencesUI/English.lproj/Localizable.strings
index 68d2a7004..ffee2363f 100644
--- a/UI/PreferencesUI/English.lproj/Localizable.strings
+++ b/UI/PreferencesUI/English.lproj/Localizable.strings
@@ -237,6 +237,7 @@
 "Calendar Category" = "Calendar Category";
 "Add Calendar Category" = "Add Calendar Category";
 "New category" = "New category";
+"Reset to defaults" = "Reset to defaults";
 "Remove Calendar Category" = "Remove Calendar Category";
 "Contact Category" = "Contact Category";
 "Add Contact Category" = "Add Contact Category";
diff --git a/UI/PreferencesUI/UIxPreferences.m b/UI/PreferencesUI/UIxPreferences.m
index 8937f76df..639b78432 100644
--- a/UI/PreferencesUI/UIxPreferences.m
+++ b/UI/PreferencesUI/UIxPreferences.m
@@ -1212,6 +1212,27 @@ static NSArray *reminderValues = nil;
   return [uniqueAddressesList componentsJoinedByString: @", "];
 }
 
+//
+// Used by templates
+//
+- (NSString *) defaultCalendarCategoriesColors
+{
+  NSArray *labels, *colors;
+  NSMutableDictionary *defaultCategoriesColors;
+  unsigned int i;
+
+  labels = [[self labelForKey: @"calendar_category_labels"] componentsSeparatedByString: @","];
+  colors = [[[SOGoSystemDefaults sharedSystemDefaults] calendarCategoriesColors] allValues];
+  defaultCategoriesColors = [NSMutableDictionary dictionary];
+  for (i = 0; i < [colors count]; i++)
+    {
+      [defaultCategoriesColors setObject: [colors objectAtIndex: i]
+                                  forKey: [labels objectAtIndex: i]];
+    }
+
+  return [defaultCategoriesColors jsonRepresentation];
+}
+
 //
 // Used by templates
 //
diff --git a/UI/Templates/PreferencesUI/UIxPreferences.wox b/UI/Templates/PreferencesUI/UIxPreferences.wox
index a4fb6d58c..b5b67043b 100644
--- a/UI/Templates/PreferencesUI/UIxPreferences.wox
+++ b/UI/Templates/PreferencesUI/UIxPreferences.wox
@@ -19,6 +19,7 @@
     var vacationEnabled = <var:string value="isVacationEnabled" const:escapeHTML="NO"/>;
     var timeZonesList = <var:string value="timeZonesList" const:escapeHTML="NO"/>;
     var defaultEmailAddresses = '<var:string value="defaultEmailAddresses" const:escapeHTML="NO"/>';
+    var defaultCalendarCategories = <var:string value="defaultCalendarCategoriesColors" const:escapeHTML="NO"/>;
     var forwardConstraints = <var:string value="forwardConstraints" const:escapeHTML="NO"/>;
     var sieveCapabilities = <var:string value="sieveCapabilities" const:escapeHTML="NO"/>;
   </script>
@@ -429,6 +430,11 @@
               </md-list>
 
               <div layout="row" layout-align="end center">
+                <md-button type="button"
+                           label:aria-label="Reset to defaults"
+                           ng-click="app.resetCalendarCategories(preferencesForm)">
+                  <var:string label:value="Reset to defaults"/>
+                </md-button>
                 <md-button type="button"
                            label:aria-label="Add Calendar Category"
                            ng-click="app.addCalendarCategory(preferencesForm)">
diff --git a/UI/WebServerResources/js/Preferences/PreferencesController.js b/UI/WebServerResources/js/Preferences/PreferencesController.js
index 29fd59dd5..f5df6eaad 100644
--- a/UI/WebServerResources/js/Preferences/PreferencesController.js
+++ b/UI/WebServerResources/js/Preferences/PreferencesController.js
@@ -3,7 +3,7 @@
 
 (function() {
   'use strict';
-  
+
   /**
    * @ngInject
    */
@@ -62,6 +62,12 @@
         });
     };
 
+    this.resetCalendarCategories = function(form) {
+      this.preferences.defaults.SOGoCalendarCategories = _.keys($window.defaultCalendarCategories);
+      this.preferences.defaults.SOGoCalendarCategoriesColors = angular.copy($window.defaultCalendarCategories);
+      form.$setDirty();
+    };
+
     this.addCalendarCategory = function(form) {
       this.preferences.defaults.SOGoCalendarCategoriesColors[l('New category')] = "#aaa";
       this.preferences.defaults.SOGoCalendarCategories.push(l('New category'));
@@ -202,10 +208,10 @@
         form.$setDirty();
       });
     };
-    
+
     this.editMailFilter = function(ev, index, form) {
       var filter = angular.copy(this.preferences.defaults.SOGoSieveFilters[index]);
-      
+
       $mdDialog.show({
         templateUrl: 'editFilter?filter=' + index,
         controller: 'FiltersDialogController',
@@ -388,7 +394,7 @@
 
       return false;
     };
-    
+
     this.changePassword = function() {
       Authentication.changePassword(this.passwords.newPassword).then(function() {
         var alert = $mdDialog.alert({