Pulse studies of the interaction of CH4 and NiO/Al2O3 catalysts at 500-degrees-C indicate that CH4 adsorption on reduced nickel sites is a key step for CH4 oxidative conversion. On an oxygen-rich surface, CH4 conversion is low and the selectivity Of CO2 is higher than that of CO. With the consumption of surface oxygen, CO selectivity increases while the CO2 selectivity falls. The conversion of CH4 is small at 500-degrees-C when a pulse of CH4/O2 (CH4 : O2 = 2 : 1) is introduced to the partially reduced catalyst, indicating that CH4 and O2 adsorption are competitive steps and the adsorption of O2 is more favorable than CH4 adsorption.