Solid oxide fuel cell (SOFC) is a clean and highly efficient electric power generator. A typical SOFC with yttria-stabilized zirconia (YSZ) electrolyte is operated at about 1273 K. A decrease of the solid electrolyte thickness enhances the power density. Rare earth-doped ceria (RDC) electrolyte has a higher oxide ion conductivity than YSZ, which is effective to lower the operation temperature of SOFC [1]. On the other hand, the electric power density is also influenced by the electrochemical properties of electrodes. Sr-doped samarium cobaltite cathode with a composition Sm0.5Sr0.5CoO3 (SSC) for SOFC with RDC electrolyte has a high electronic conductivity of 103 S/cm at 769-1176 K [2]. In addition, SSC has a lower overpotential than LaxSr1-xCoO3 [3]. In this study, SSC and RuO2-doped SSC were characterized as a cathode of SOFC with Sm-doped ceria (SDC) electrolyte. Ni-SDC anode was also prepared to evaluate the cell.