The reactions of propane or propene with (NO)-N-15 in the absence or presence of oxygen on Na-, H-, and CuZSM-5 zeolites have been investigated using N-15 solid state nuclear magnetic resonance (NMR) spectroscopy. The nitrogen-containing surface species and gas phase products formed by these reactions under conditions of thermal equilibrium were monitored and identified by N-15 NMR. The role of the hydrocarbon reductant, oxygen and the exchangeable cation in the selective catalytic reduction of NO by hydrocarbons (SCR-HC) was examined in this study.