Direct oxidation of composite Ni/Ti metal film structure for AlGaN/GaN MOSHEMT has been successfully demonstrated. In comparison with normal HEMT with Schottky-gate, transistors fabricated with this novel process exhibit three orders of magnitude reduction in gate leakage current, superior breakdown voltage (V-br = 471 V vs. 88 V for normal HEMT) and electrical stability (similar to 0.3% electric field stress induced drain current degradation versus similar to 6% for normal HEMT after 25 V drain bias). The drastic improvement in device performance stability, renders the new process highly promising for GaN based, microwave power amplifier applications in communication and radar systems. (C) 2010 Elsevier Ltd. All rights reserved.