Oxidation of 4H-SiC proceeds at 600 degrees C by use of nitric acid vapor. The plots of the SiO2 thickness vs. the square root of the oxidation time are linear, indicating that diffusion of oxidizing species is the rate-determining step. The initial oxidation rate of the C-faced surfaces is 3 times higher than that of the Si-faced surfaces. It is found from cross-sectional transmission electron micrography (TEM) measurements that the SiO2 thickness is uniform and steps originating from miss-orientation from the (000-1) direction having 0.25 nm height are present before and after oxidation, showing that oxidation of SiC proceeds only from step-edges along the (-1100) direction for the C-face and the (1-100) direction for the Si-face. (c) The Author(s) 2017. Published by ECS. All rights reserved.