The electrical characteristics of 4H-SiC junction gated MOSFETs (JMOSFETs) have been investigated by 2-dimensional device simulations. The results have been compared with measured data from 300 K to 573 K. and applied to predict the device performance up to 773 K. Simulation results predict a decrease of the saturation current to 7.5% of its room temperature value as the temperature increases from 300 K to 773 K. However, by applying a proper voltage on the top MOS gate, carrier accumulation can be used to compensate for the reduced mobility and a constant drain current can be maintained over the whole temperature range (300 K - 773 K), where the main deviations for different temperatures are at low drain voltages before the drain current saturates.