Thin-Pt SiC Schottky diodes on 4H- and 6H-SiC substrates responding to NO gas at high temperature were fabricated. Schottky barrier height, ideality factor and series resistance were evaluated from linear G/I x G plots. Upon exposure to NO gas, the forward current of the devices increases due to a reduction of the Schottky barrier height. This reduction is slightly larger for 6H-SiC Schottky diodes. The devices were tested for NO gas concentrations from 5 ppm to 50 ppm and showed reversible and stable response at temperatures up to 450 degreesC.