The reaction of carbon dioxide catalytic reforming with methane is an attractive route because these greenhouse gases can be converted into variable feedstocks. However this reaction is a highly energy consuming and coke forming process. These problems were improved by the electrocatalytic reforming of CO2 with CH4 in a solid oxide fuel cell (SOFC) membrane reactor system, which generates high electrical power and synthesis gases. The single cell consists of catalyst electrode (NiO-MgO), counter electrode ((La,Sr)MnO3) and Y2O3 stabilized ZrO2 (YSZ) electrolyte. The reaction rates of CO2 and CH4, and the electrochemical properties were investigated by an on-line GC and impedance-analyzer under open- and closed-circuit conditions, respectively. It was found that reaction rates of O-2 and CH4 under the closed-circuit condition were more stable than those of the open-circuit. The results were interpreted that the stability of catalyst anode was maintained by the reaction of oxygen ion transferred from the cathode with the surface carbon formed in the internal CO2 reforming by CH4 in SOFC system. (C) 2003 Elsevier B.V. All rights reserved.