The infrared (IR) chemiluminescence technique was applied to steady-state CO oxidation by N on Pd(111) and Pd(110). From a comparison of IR emission spectra of CO2 between the CO + NO and CO + O-2 reactions, it was found that the vibrational energy states of CO2 in the CO + NO reaction were similar to those in the CO + O-2 reaction. This indicates that the reaction path of CO2 formation in CO + NO is the same as that in CO + O-2, although the vibrational states are very dependent on the surface structure.