The major limitation when using the BuilderSupport is it doesn't support the multiple namespaces which is very common. E.g. I want to create the XML message to invoke Google calendar <entry xmlns='http://www.w3.org/2005/Atom' xmlns:gCal='http://schemas.google.com/gCal/2005'> <content type="html">Tennis with John April 11 3pm-3:30pm</content> <gCal:quickadd value="true"/> </entry> I cannot build the message with current NamespaceBuilderSupport for there is only one namespace could be specified. So, I create one NamespaceBuilderSupport then I can create the message in Groovy. def builder = new NamespaceBuilderSupport (DOMBuilder.newInstance()); builder.namespace('http://www.w3.org/2005/Atom'); builder.namespace('http://schemas.google.com/gCal/2005', 'gCal') def data = builder.entry { "gCal:quickadd"(value:"true") title("Tennis with John") content(type:'html', "Tennis with wen Bing in PKU on February 5 3pm-3:30pm") } And the reference impl is as following. public class NamespaceBuilderSupport extends BuilderSupport{ private Map<String, String> nsMap = new HashMap<String, String>(); public NamespaceBuilderSupport(BuilderSupport builder) { super(builder); } protected NamespaceBuilderSupport namespace(String namespaceURI) { nsMap.put("", namespaceURI); return this; } protected NamespaceBuilderSupport namespace(String namespaceURI, String prefix) { nsMap.put(prefix, namespaceURI); return this; } protected Object getName(String methodName) { String prefix = ""; String localPart = methodName; int idx = methodName.indexOf(':'); if (idx > 0 ) { prefix = methodName.substring(0, idx); localPart = methodName.substring(idx + 1); } String namespaceURI = nsMap.get(prefix); if (namespaceURI == null) { namespaceURI = ""; prefix = ""; } return new QName(namespaceURI, localPart, prefix); } @Override protected Object createNode(Object name) { return name; } @Override protected Object createNode(Object name, Object obj1) { return name; } } @Override protected Object createNode(Object name, Map map) { return name; } @Override protected Object createNode(Object name, Map map, Object obj1) { return name; } } @Override protected void setParent(Object obj, Object obj1) { } } Thanks in advance. I hope it could be helpful.