Single-, 15-, and 30-layered Cr-N coatings deposited on a steel substrate were oxidized in air at 700 and 800 degrees C. Oxidation occurred via the predominant outward diffusion of Cr, Fe, and nitrogen, and the inward diffusion of oxygen. Nitrogen escaping from the coating into the air made the multi-layered Cr-N coating act as a single-layered Cr-N coating during oxidation. The oxidation product was primarily Cr2O3, which contained a small amount of Fe and nitrogen. The unreacted coating beneath the Cr2O3 scale had some iron transported from the substrate. (c) 2005 Elsevier B.V. All rights reserved.