The reduction of NO with CO on a perovskite catalyst, LaCoOs3 was investigated by means of steady state isotopic transient kinetic analysis (SSITKA). Steady stake reactions were carried out at temperatures of 300-700 degrees C, while the isotopic transient experiments were carried out at temperatures of 500-700 degrees C. Isotopic switches of (CO)-C-12 to (CO)-C-13 or (NO)-N-14 to (NO)-N-15 were performed after the reaction reached steady state. In order to determine the effect of readsorption, experiments at various temperatures were carried out as a function of space velocity. The SSITKA results for NO reduction with CO indicated that all the species (reactants and products) had measurable surface lifetimes and concentrations on the catalyst surface at various temperatures, Both the steady state and the SSITKA results were consistent with N2O being a precursor in the formation of Nz at temperatures below 600 degrees C. SSITKA results indicated that the entire catalyst surface was involved in the reaction, and that, at high temperature, CO2 desorption became limiting for the overall reaction. This was most likely due to the rapid formation and slow decomposition of carbonates on the surface.