Silicon Carbide has been proposed as a preferred material for high-power, high temperature semiconductor devices, primarily because of its large energy-bandgap and high thermal conductivity. Heterojunction bipolar transistors with a GaN wide bandgap emitter and SiC base and collector region have recently been demonstrated to have very high DC current gain (>100,000) and have been operated up to 260/spl deg/C. We present the first operation of a semiconductor bipolar transistor at a temperature of 500/spl deg/C with a current gain greater than 100. The GaN/SiC n-p-n HBT's common base I-V characteristics, current gain versus emitter current curves, and Gummel plots were obtained at temperatures ranging from 25/spl deg/C to 535/spl deg/C. The I-V characteristics showed little change over this temperature range, except for an increase in leakage current with increasing temperature. Only common base characteristics were obtained due to the high gain of the devices and the leakage current between base and collector. The high temperature of operation and the large gain even at elevated temperatures indicate the extraordinary potential of these devices for high-temperature and high-power operation.