The reduced temperature solid oxide fuel cell (SOFC) with 0.5 mm thick La0.9Sr0.1Ga0.8Mg0.2O3-alpha (LSGM) electrolyte, La0.6Sr0.4CoO3-delta (LSCo) cathode, and Ni-(CeO2)(0.8)(SmO1.5)(0.2) (SDC) cermet anode showed an excellent initial performance, and high maximum power density, 0.47 W/cm(2), at 800 degrees C. The results were comparable to those for the conventional SOFC with yttria-stabilized zirconia (YSZ) electrolyte, La(Sr)MnO3-YSZ cathode and Ni-YSZ cermet anode at 1000 degrees C. Using an LSCo powder prepared by spray pyrolysis, and selecting appropriate sintering temperatures, the lowest cathodic polarization of about 25 mV at 300 mA/cm(2) was measured for a cathode prepared by sintering at 1000 degrees C. Life time cell test results, however, showed that the polarization of the LSCo cathode increased with operating time. From EPMA results, this behavior was considered to be related to the interdiffusion of the elements at the cathode/electrolyte interface. Calcination of LSCo powder could be a possible way to suppress this interdiffusion at the interface.