In this study, a new oxygen-deficient cathode material, Sm0.5Sr0.5Co1-xCuxO3-delta (SSCCu) was developed. It is expected to enhance the efficiency of intermediate-temperature solid oxide fuel cells (IT-SOFCs). The structure, conductivity and electrochemical performance of SSCCu were examined as a function of copper content. The structure of Sm0.5Sr0.5Co0.9Cu0.1O3-delta and Sm0.5Sr0.5Co0.8Cu0.2O3-delta samples was a single orthorhombic perovskite phase. Second phase SrCoO2.8, however, formed in the Sm0.5Sr0.5Co0.7Cu0.3O3-delta and Sm0.5Sr0.5Co0.6Cu0.4O3-delta samples. The conductivity of the Sm0.5Sr0.5Co0.7Cu0.3O3-delta cathode was higher than that of other samples. However, the Sm0.5Sr0.5Cu0.8Cu0.2O3-delta electrode exhibited the lowest overpotential of 25 nnV at 400 mA cm(-2) and the lowest area special resistance of 0.2 Omega cm(2) at 700 degrees C. (C) 2008 Elsevier B.V. All rights reserved.