The perovskite-type Ba0.5Sr0.5Co0.8Fe0.2O3-delta-BaZr0.1Ce0.7Y0.2O3-delta (BSCF-BZCY) composite oxides were synthesized by a modified Pechini method and examined as a novel composite cathode for intermediate-to-low temperature protonic ceramic membrane fuel cells (ILT-PCMFCs). Thin proton-conducting BaZr0.1Ce0.7Y0.2O3-delta (BZCY) electrolyte and NiO-BaZrotCe0.7Y0.203-8 (NiO-BZCY) anode functional layer were prepared over porous anode substrates composed of NiO-BaZr0.1Ce0.7Y0.2O3-delta by a one-step dry-pressing/co-firing process. A laboratory-sized quad-layer cell of NiO-BZCY/NiO-BZCY(similar to 50 mu m)/BZCY(similar to 20 mu m)/BSCF-BZCY(similar to 50 mu m) was operated from 550 to 700 degrees C with humidified hydrogen (similar to 3% H2O) as fuel and the static air as oxidant. A high open-circuit potential of 1.009V, a maximum power density of 418 mW cm(-2), and a low polarization resistance of the electrodes of 0.10 Omega cm(2) was achieved at 700 degrees C. These investigations have indicated that proton-conducting BZCY electrolyte with BSCF perovskite cathode is a promising material system for the next generation solid oxide fuel cells (SOFCs). (c) 2008 Elsevier B.V. All rights reserved.