We use the high–low capacitance–voltage technique and the conductance–frequency techniques to characterize the SiO2/SiC interface formed by thermal oxidation of the silicon‐face (0001)c‐axis, the (112¯0)a‐axis, and the (11¯00)a‐axis orientations of 6H–SiC. The oxidation rate of thea‐axis orientations is 3–5 times higher than that of the silicon face. Interface state densities on thea‐axis orientations are a factor of 4–10 times higher than the Si‐facec‐axis orientation for bothn‐type andp‐type dopings. Maximum oxide electric breakdown fields are about 10–11 MV/cm for botha‐axis andc‐axis orientations for an oxide thickness of about 60 nm. ©1996 American Institute of Physics.