The do characteristics of MgO/GaN MOSFETs were simulated over the temperature range 298-773 K using a drift-diffusion model. The saturation drain current decreases by less than a factor of two over this temperature range for a large window of MgO thicknesses (100-800 Angstrom) and gate lengths (0.5-1 mum). Similarly, gate breakdown voltage shows a very weak dependence on temperature, suggesting that the GaN MOSFETs will be well-suited for high temperature applications. (C) 2003 Elsevier Science Ltd. All rights reserved.