Hi Thanks for the feedback. It turned out that the authentication was what was getting me stuck. This is what eventually worked: <?php $order = “[API order no]"; $data = http_build_query(array("order[status]" => "S")); $email = “"; $password = “[password]"; $url = "[API URL]/$order"; $ch=curl_init(); curl_setopt($ch,CURLOPT_URL, $url); curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_BASIC ) ; curl_setopt($ch, CURLOPT_USERPWD, "$email:$password"); curl_setopt($ch, CURLOPT_SSLVERSION,3); curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE); curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2); curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "PUT"); curl_setopt($ch, CURLOPT_POSTFIELDS, $data); curl_exec($ch); curl_close($ch); ?> Regards Mills