A 4.1x4.1mm2, 100mΩ 1,2kV lateral channel vertical junction field effect transistor (LCVJFET) built in silicon carbide (SiC) from SiCED, to use as the active switch component in a high-temperature operation DC/DC-boost converter, has been investigated. The switching loss for room temperature (RT) and on-state resistance (Ron) for RT up to 170°C is investigated. Since the SiC VJFET has a buried body diode it is also ideal to use instead of a switch and diode setup. The voltage drop over the body diode decreases slightly with a higher temperature. A short-circuit test has also been conducted, which shows a high ruggedness.