The chemisorption of NO on the carbon pretreated Rh{331} single crystal surface has been investigated by XPS, LEED and SIMS. The carbon overlayer was prepared by dehydrogenation of chemisorbed C 2H 4. Results of NO adsorption at room temperature show that surface carbon blocks adsorption sites that normally coordinate molecular NO ADS and its dissociated products, N Ads and O Ads, as determined by comparing to experiments performed on clean Rh{331}. Heating the surface which contains NO Ads, n Ads, O Ads and C Ads, induces a series of chemical reactions starting with the dissociation of molecular NO Ads. Above 400 K, the C Ads and N Ads atoms combine to form CN −. The formation of the latter species is confirmed by the temperature evolution of the Rh 2CN + and CN − SIMS ion yields. The C Ads species also reacts with O Ads to produce CO and/or CO 2. These processes occur preferentially over the desorption of N 2 and O 2. In general, it is demonstrated that by using the XPS and SIMS methods, it is possible to identify the reaction species present on the surface at any given temperature and to unravel rather complex reaction pathways.