A Sm0.5Sr0.5CoO3-delta-Ce0.8Sm0.2O2-delta (SSC-SOC) composite is employed as a cathode for proton-conducting solid oxide fuel cells (H-SOFCs). BaZr0.1Ce0.7Y0.2O3-delta (BZCY) is used as the electrolyte, and the system exhibits a relatively high performance. An extremely low electrode polarization resistance of 0.066 Omega cm(2) is achieved at 700 degrees C. The maximum power densities are: 665, 504, 344, 214, and 118 mW cm(-2) at 700, 650, 600, 550, and 500 degrees C, respectively. Moreover, the SSC-SDC cathode shows an essentially stable performance for 25 h at 600 degrees C with a constant Output voltage of 0.5 V. This excellent performance implies that SSC-SDC, which is a typical cathode material for SOFCs based on oxide ionic conductor, is also a promising alternative cathode for H-SOFCs. (C) 2009 Elsevier B.V. All rights reserved.