An electrochemical cell, PdYSZPd, was constructed in order to remove both NO and CH4 in the presence of excess oxygen. When direct current was supplied to the cell with a flow of a mixture of NO, CH4, O-2, H2O and CO2 at 700 degrees C, NO was reduced to nitrogen at the cathode, and CH4 was oxidized to COx at both the anode and cathode. At the cathode, the reduction of NO and the oxidation of CH4 proceeded with the removal of chemisorbed oxygen species from the Pd surface, and at the anode, the oxidation of CH4 was enhanced by forming an active oxygen atom.