In an earlier kinetic analysis we predicted the mechanistic importance of the formation of N2O and its subsequent reaction with CO in the overall NO + CO reaction system. This work has confirmed the previous theoretical findings through steady-state and transient pulse experiments using Rh catalysts supported on alumina, ceria, and modified ceria. Results have revealed that, in agreement with the theoretical analysis, the observed suppression of the product selectivity to N2O during the NO + CO reaction at high temperatures is due to the fast N2O + CO reaction following the formation of N2O. Detailed analysis of the existing kinetic data in the literature indicates that the sticking coefficient of N2O under typical reaction conditions is extremely small (approximately 2 x 10(-6)) and thus the rate-limiting step of the isolated N2O + CO reaction is the adsorption of N2O onto the catalyst surface. Both the overall reaction pathways and the lightoff behavior of the NO + CO reaction system are discussed in light of these experimental findings. This study also serves to elucidate the nature of the low-temperature N2 desorption step (i.e., NO(a) + N(a) --> N2 + O(a) + S) previously reported in the literature.