Co-Na-MOR was prepared by ion-exchange of Na-MOR with an aqueous solution of cobalt acetate (Co-Na-MOR-9.2-104, Si/Al=9.2, and cobalt-exchange percentage = 104). We studied the catalytic activity of this sample (i) for the SCR of N2O, (ii) for the SCR of NO, and (iii) for the simultaneous SCR of N2O and NO, where SCR stands for “Selective Catalytic Reduction with CH4 in the presence of O2”. Catalytic measurements were performed in a flow apparatus with GC analysis of reactants and products. Results show that Co-Na-MOR is active and selective (i) in the SCR of N2O, (ii) in the SCR of NO and (iii) in the simultaneous SCR of N2O and NO. The NO conversion in the simultaneous SCR of NO and N2O equalled that in the SCR of NO. Analogously, the N2O conversion in the simultaneous SCR of NO and N2O equalled that in the SCR of N2O. These findings strongly suggest that on Co-Na-MOR the simultaneous SCR of NO and N2O consists of two independent reactions: the SCR of NO, and the SCR of N2O. We conclude that Co-Na-MOR can be used as an effective catalyst in a process causing the simultaneous SCR of N2O and NO, using CH4 alone as the reducing agent, in the presence of excess O2.