Description: ------------ On line 97 in the function toString the timezone is converted with the default PHP convert string O . This is false. The PHP use for timezone the pattern +0200 , but the XSD defines the pattern +02:00 (see http://www.w3.org/TR/xmlschema-2/#dateTime-timezones). The source code should be modified to be XSD compatible. Test script: --------------- You should add following function: /** * Converts PHP timezone String to XSD compatible timezone String. * see http://www.w3.org/TR/xmlschema-2/#dateTime-timezones * @param string $timeZoneStr a PHP timezone string * @return string An XSD compatible timezone string */ function timeZoneToXSD($timeZoneStr) { if(strlen($timeZoneStr)!=5) { return $timeZoneStr; } return substr($timeZoneStr,0,3) . ":" . substr($timeZoneStr,3,2); } and substitute the line 97 with following: return date('Y-m-d\TH:i:s', $timestamp) . $this->timeZoneToXSD(date('O', $timestamp)) ;