<?php
$dom = new DOMDocument('1.0', 'iso-8859-1');
$element = $dom->createElementNS('http://www.example.com/XFoo', 'xfoo:test', 'This is the root element!');
// We insert the new element as root (child of the document)
$dom->appendChild($element);
echo $dom->saveXML();
?>
The above example will output:
<?xml version="1.0" encoding="iso-8859-1"?>
<xfoo:test xmlns:xfoo="http://www.example.com/XFoo">This is the root element!</xfoo:test>