Abstract Oxide films up to 2500 å thick have been grown on SiC by anodizing p- or n-type crystals in a constant current mode, in a diethylene glycol-KNO 3 solution. Several features of the anodization process are reported here for the first time. Using ellipsometric analysis, the refractive index of the films was measured to be 1.46 at 5460 å. This and other results suggest that silicon dioxide is formed during anodization. Certain discrepancies that make further confirmation necessary are discussed.