The structure sensitive reaction, CO+NO, has been studied on two crystal planes of palladium. The Pd(lll) surface was found to be approximately five times more active than Pd(100) for NO reduction by CO. This structure sensitivity is attributed primarily to the stabilization of molecularly adsorbed NO (NOa) relative to N-a on Pd(lll) vs Pd(100). It has also been found that the Pd(100) surface is more effective at dissociating NOa than Pd(lll). As a result, Pd(100) yields a higher ratio of N-2/N2O compared to Pd(lll). Pd(ZOO), however, also stabilizes atomic nitrogen on the surface, resulting in the poisoning of subsequent NO adsorption/dissociation and thus inhibiting the overall CO+NO reaction.