The expected high-temperature dc characteristics of Sc2O3/GaN metal-oxide semiconductor field-effect transistors (MOSFETs) were simulated over the temperature range 298-773 K using a drift-diffusion model. The gate breakdown voltage (V-B) shows a very weak dependence on temperature in this range due to the wide bandgap of GaN, with a decrease of V-B<15%. The saturation drain current decreased by less than a factor of two over this temperature range for Sc2O3 thicknesses in the range 100-800 &ANGS; and gate lengths from 0.5 to 1 μm. Given the additional advantage of the effectiveness of Sc2O3 as a surface passivant on GaN-based transistors, MOSFETs using this material as a gate dielectric appear promising for high-temperature applications. (C) 2003 The Electrochemical Society.