Assumed, we got a fully parsed org.w3c.dom.Document: Just using LSSerializer‘s writeToString method without specifying any encoding will result in (rather impractical) UTF-16 encoded xml file per default will output Unfortunately, specifying an encoding isn’t trivial. Here are two solutions that don’t require any third party libraries: 1. Using org.w3c.dom.ls.LSOutput 2. Using javax.xml.transform.Transformer