Anode-supported solid oxide fuel cells (SOFCs) based on gadolinia-doped ceria (GDC, Gd0.1Ce0.9O1.95) are fabricated by a simple and cost-effective dry-pressing process. With a composite anode consisting of NiO + 35 wt.% GDC and a composite cathode consisting of Sm0.5Sr0.5CoO3 (SSC) and 10 wt.% GDC, the cells are tested at temperatures from 400 to 650 degreesC. When humidified (3% H2O) hydrogen is used as fuel and stationary air as oxidant, the maximum power densities are 145 and 400 mW/cm(2) at 500 and 600 degreesC, respectively. Impedance analysis indicates that the performances of the SOFCs are determined essentially by the interfacial resistances below 550 degreesC. Further, while the anodic polarization resistances are negligible, the cathodic polarization resistances are significant, suggesting that development of new cathode materials is especially important to SOFCs to be operated at low temperatures.