Enhancement-type n-channel metal-oxide-semiconductor field effect transistors (MOSFETs) have been fabricated on p-type 6H-SiC epitaxial films. The gate oxide in the MOSFETs was annealed in steam or dry hydrogen (H-2) up to 1000 degreesC to investigate the influence of post-oxidation annealing on the electrical characteristics of the MOSFETs. The channel mobility is found to increase by both annealing methods. The optimum annealing temperature is obtained to be 800 degreesC for steam annealing and 700 degreesC for annealing in H-2.