An electrochemical cell, Pd\YSZ\Pd, was constructed to remove both NO and CH4 from an oxidizing atmosphere. When the direct current was supplied to the cell at 700 degrees C in the reactant flow containing 1000 ppm NO, 1000 ppm CH4 and an excess amount of O-2, NO was reduced to N-2 at the cathode, and CH4 was oxidized to COx at the anode.