Inversion mode n-channel MOSFETs have been built on (6H) silicon carbide (SiC) substrates, with thermal oxide as the gate insulator, and with channel lengths ranging from 1 to 25 mu m. Drain leakage currents lower than 0.04pA/mu m channel width have been experimentally obtained at temperatures up to 400 degrees C and V-d = 5V.