The carbon dioxide reforming by methane over Ni-YSZ-CeO2 catalyst electrode in an electrochemical cell (CO2, CH4, Ni-YSZ-CeO2\YSZ\La0.79Sr0.16Mn0.8Co0.2O3, air) under open- and short-circuit conditions was studied at 800degreesC and atmospheric pressure. The microstructure of the catalyst electrode was characterized by SEM. The current-voltage test showed that the electric power generation performance of the electrochemical cell for methane and carbon dioxide was close to that for hydrogen. Under open-circuit condition, the catalyst electrode was deactivated by coke deposition. On the other hand, the catalyst electrode was stable and the selectivity of carbon monoxide was increased under short-circuit condition. The electrochemically pumped oxygen ion was reacted with the surface carbon which formed in the dry reforming on the three boundary phase (Ni/YSZ/gas) to yield carbon monoxide.