<html xmlns="http://www.w3.org/1999/xhtml"> <head> <script> function foo() { var m = "http://www.w3.org/1998/Math/MathML"; var newTable = document.createElementNS(m, "mtable") document.getElementById("mtable").appendChild(newTable); } </script> </head> <body onload="foo()"> <div> <math xmlns="http://www.w3.org/1998/Math/MathML" display="block"> <mtable id="mtable"> <mtr id="mtr"> <mtd> <mi>x</mi> </mtd> </mtr> </mtable> </math> </div> </body> </html>