Silicon carbide bipolar junction transistors were fabricated in the study reported here. Three-dimensional thermal simulations were conducted for the SiC BJTs using FEMLAB. Thermal images of a device under operation were also recorded using an infrared camera. Both the simulations and the measurement show a significant temperature increase in the vicinity of the device when operated at high power densities, thus causing the decrease in the DC current gain. The junction temperature extracted during self-heating was approximately 154 degreesC at a power dissipation of 5.5W, using the assumption that the current gain only depends on the temperature. The simulation results show a junction temperature of 157 degreesC at the same power level. Long-term stability tests over 80 hours were also performed at elevated temperatures, and a 10% decrease in the current gain was observed.