diff --git a/plugins/calendar/drivers/kolab/kolab_calendar.php b/plugins/calendar/drivers/kolab/kolab_calendar.php
index 44465ebb..8667b4da 100644
--- a/plugins/calendar/drivers/kolab/kolab_calendar.php
+++ b/plugins/calendar/drivers/kolab/kolab_calendar.php
@@ -325,10 +325,13 @@ class kolab_calendar extends kolab_storage_folder_api
         // skip the first instance of a recurring event if listed in exdate
         if ($virtual && !empty($event['recurrence']['EXDATE'])) {
           $event_date = $event['start']->format('Ymd');
-          $exdates = (array)$event['recurrence']['EXDATE'];
+          $event_tz   = $event['start']->getTimezone();
 
-          foreach ($exdates as $exdate) {
-            if ($exdate->format('Ymd') == $event_date) {
+          foreach ((array) $event['recurrence']['EXDATE'] as $exdate) {
+            $ex = clone $exdate;
+            $ex->setTimezone($event_tz);
+
+            if ($ex->format('Ymd') == $event_date) {
               $add = false;
               break;
             }
diff --git a/plugins/libcalendaring/libvcalendar.php b/plugins/libcalendaring/libvcalendar.php
index 06e660b8..0a33798a 100644
--- a/plugins/libcalendaring/libvcalendar.php
+++ b/plugins/libcalendaring/libvcalendar.php
@@ -1072,19 +1072,18 @@ class libvcalendar implements Iterator
 
             // add EXDATEs each one per line (for Thunderbird Lightning)
             if (is_array($exdates)) {
-                foreach ($exdates as $ex) {
-                    if ($ex instanceof \DateTime) {
-                        $exd = clone $event['start'];
-                        $exd->setDate($ex->format('Y'), $ex->format('n'), $ex->format('j'));
-                        $exd->setTimeZone(new \DateTimeZone('UTC'));
-                        $ve->add($this->datetime_prop($cal, 'EXDATE', $exd, true));
+                foreach ($exdates as $exdate) {
+                    if ($exdate instanceof DateTime) {
+                        $ve->add($this->datetime_prop($cal, 'EXDATE', $exdate));
                     }
                 }
             }
             // add RDATEs
-            if (!empty($rdates)) {
-                foreach ((array)$rdates as $rdate) {
-                    $ve->add($this->datetime_prop($cal, 'RDATE', $rdate));
+            if (is_array($rdates)) {
+                foreach ($rdates as $rdate) {
+                    if ($ex instanceof DateTime) {
+                        $ve->add($this->datetime_prop($cal, 'RDATE', $rdate));
+                    }
                 }
             }
         }
diff --git a/plugins/libkolab/lib/kolab_format.php b/plugins/libkolab/lib/kolab_format.php
index 4f55a502..cde67fad 100644
--- a/plugins/libkolab/lib/kolab_format.php
+++ b/plugins/libkolab/lib/kolab_format.php
@@ -203,17 +203,20 @@ abstract class kolab_format
      * @param mixed         Date/Time value either as unix timestamp, date string or PHP DateTime object
      * @param DateTimeZone  The timezone the date/time is in. Use global default if Null, local time if False
      * @param boolean       True of the given date has no time component
-     * @return object       The libkolabxml date/time object
+     * @param DateTimeZone  The timezone to convert the date to before converting to cDateTime
+     *
+     * @return cDateTime The libkolabxml date/time object
      */
-    public static function get_datetime($datetime, $tz = null, $dateonly = false)
+    public static function get_datetime($datetime, $tz = null, $dateonly = false, $dest_tz = null)
     {
-        // use timezone information from datetime of global setting
+        // use timezone information from datetime or global setting
         if (!$tz && $tz !== false) {
             if ($datetime instanceof DateTime)
                 $tz = $datetime->getTimezone();
             if (!$tz)
                 $tz = self::$timezone;
         }
+
         $result = new cDateTime();
 
         try {
@@ -225,14 +228,26 @@ abstract class kolab_format
             else if (is_string($datetime) && strlen($datetime)) {
                 $datetime = $tz ? new DateTime($datetime, $tz) : new DateTime($datetime);
             }
+            else if ($datetime instanceof DateTime) {
+                $datetime = clone $datetime;
+            }
         }
         catch (Exception $e) {}
 
         if ($datetime instanceof DateTime) {
+            if ($dest_tz instanceof DateTimeZone && $dest_tz !== $datetime->getTimezone()) {
+                $datetime->setTimezone($dest_tz);
+                $tz = $dest_tz;
+            }
+
             $result->setDate($datetime->format('Y'), $datetime->format('n'), $datetime->format('j'));
 
-            if (!$dateonly)
-                $result->setTime($datetime->format('G'), $datetime->format('i'), $datetime->format('s'));
+            if ($dateonly) {
+                // Dates should be always in local time only
+                return $result;
+            }
+
+            $result->setTime($datetime->format('G'), $datetime->format('i'), $datetime->format('s'));
 
             // libkolabxml throws errors on some deprecated timezone names
             $utc_aliases = array('UTC', 'GMT', '+00:00', 'Z', 'Etc/GMT', 'Etc/UTC');
@@ -254,16 +269,19 @@ abstract class kolab_format
     /**
      * Convert the given cDateTime into a PHP DateTime object
      *
-     * @param object cDateTime  The libkolabxml datetime object
-     * @return object DateTime  PHP datetime instance
+     * @param cDateTime    The libkolabxml datetime object
+     * @param DateTimeZone The timezone to convert the date to
+     *
+     * @return DateTime PHP datetime instance
      */
-    public static function php_datetime($cdt)
+    public static function php_datetime($cdt, $dest_tz = null)
     {
-        if (!is_object($cdt) || !$cdt->isValid())
+        if (!is_object($cdt) || !$cdt->isValid()) {
             return null;
+        }
 
         $d = new DateTime;
-        $d->setTimezone(self::$timezone);
+        $d->setTimezone($dest_tz ?: self::$timezone);
 
         try {
             if ($tzs = $cdt->timezone()) {
diff --git a/plugins/libkolab/lib/kolab_format_xcal.php b/plugins/libkolab/lib/kolab_format_xcal.php
index d6d34422..a08d0aa0 100644
--- a/plugins/libkolab/lib/kolab_format_xcal.php
+++ b/plugins/libkolab/lib/kolab_format_xcal.php
@@ -174,6 +174,10 @@ abstract class kolab_format_xcal extends kolab_format
             }
         }
 
+        if ($object['start'] instanceof DateTime) {
+            $start_tz = $object['start']->getTimezone();
+        }
+
         // read recurrence rule
         if (($rr = $this->obj->recurrenceRule()) && $rr->isValid()) {
             $rrule_type_map = array_flip($this->rrule_type_map);
@@ -185,7 +189,7 @@ abstract class kolab_format_xcal extends kolab_format
             if (($count = $rr->count()) && $count > 0) {
                 $object['recurrence']['COUNT'] = $count;
             }
-            else if ($until = self::php_datetime($rr->end())) {
+            else if ($until = self::php_datetime($rr->end(), $start_tz)) {
                 $refdate = $this->get_reference_date();
                 if ($refdate && $refdate instanceof DateTime && !$refdate->_dateonly) {
                     $until->setTime($refdate->format('G'), $refdate->format('i'), 0);
@@ -214,16 +218,18 @@ abstract class kolab_format_xcal extends kolab_format
 
             if ($exdates = $this->obj->exceptionDates()) {
                 for ($i=0; $i < $exdates->size(); $i++) {
-                    if ($exdate = self::php_datetime($exdates->get($i)))
+                    if ($exdate = self::php_datetime($exdates->get($i), $start_tz)) {
                         $object['recurrence']['EXDATE'][] = $exdate;
+                    }
                 }
             }
         }
 
         if ($rdates = $this->obj->recurrenceDates()) {
             for ($i=0; $i < $rdates->size(); $i++) {
-                if ($rdate = self::php_datetime($rdates->get($i)))
+                if ($rdate = self::php_datetime($rdates->get($i), $start_tz)) {
                     $object['recurrence']['RDATE'][] = $rdate;
+                }
             }
         }
 
@@ -415,6 +421,10 @@ abstract class kolab_format_xcal extends kolab_format
             $this->obj->setOrganizer($organizer);
         }
 
+        if ($object['start'] instanceof DateTime) {
+            $start_tz = $object['start']->getTimezone();
+        }
+
         // save recurrence rule
         $rr = new RecurrenceRule;
         $rr->setFrequency(RecurrenceRule::FreqNone);
@@ -470,13 +480,13 @@ abstract class kolab_format_xcal extends kolab_format
             if ($object['recurrence']['COUNT'])
                 $rr->setCount(intval($object['recurrence']['COUNT']));
             else if ($object['recurrence']['UNTIL'])
-                $rr->setEnd(self::get_datetime($object['recurrence']['UNTIL'], null, true));
+                $rr->setEnd(self::get_datetime($object['recurrence']['UNTIL'], null, true, $start_tz));
 
             if ($rr->isValid()) {
                 // add exception dates (only if recurrence rule is valid)
                 $exdates = new vectordatetime;
                 foreach ((array)$object['recurrence']['EXDATE'] as $exdate)
-                    $exdates->push(self::get_datetime($exdate, null, true));
+                    $exdates->push(self::get_datetime($exdate, null, true, $start_tz));
                 $this->obj->setExceptionDates($exdates);
             }
             else {
@@ -494,7 +504,7 @@ abstract class kolab_format_xcal extends kolab_format
         if (!empty($object['recurrence']['RDATE'])) {
             $rdates = new vectordatetime;
             foreach ((array)$object['recurrence']['RDATE'] as $rdate)
-                $rdates->push(self::get_datetime($rdate, null, true));
+                $rdates->push(self::get_datetime($rdate, null, true, $start_tz));
             $this->obj->setRecurrenceDates($rdates);
         }
 
@@ -760,7 +770,7 @@ abstract class kolab_format_xcal extends kolab_format
             $error_logged = true;
             rcube::raise_error(array(
                 'code'    => 900,
-                'message' => "required kolabcalendaring module not found"
+                'message' => "Required kolabcalendaring module not found"
             ), true);
         }