The electrochemical performance of Pr0.7Sr0.3Co0.9Cu0.1O3-delta-xCe(0.8)Sm(0.2)O(1.9)(PSCC-xSDC, x = 0-40 wt%) composite cathodes has been investigated for their potential utilization in intermediate-temperature solid oxide fuel cells (SOFCs). The results showed that the addition of SDC to PSCC improved remarkably the electrochemical performance of a PSCC cathode, and that a PSCC-35SDC cathode exhibited the best electrochemical performance in the PSCC-xSDC system. When SDC was used as the electrolyte, the interfacial resistance was smallest for 35 wt% SDC, where the value was 0.137 Omega cm(2) at 700 degrees C and 0.062 Omega cm(2) at 750 degrees C, much lower than the corresponding interfacial resistance for pure PSCC. At 700 degrees C, the cathodic overpotential of the PSCC-35SDC cathode in the SDC electrolyte was 70 mV at a current density of 0.5 A cm(-2). This is a factor of two lower than that for a pure PSCC cathode (152 mV at 700 degrees C) under the same current conditions. The maximum power density of a single-cell using PSCC-35SDC as the cathode was 388 and 615 mW cm(-2) at 650 and 700 degrees C, respectively. (c) 2008 Elsevier B.V. All rights reserved.