Sm1.8Ce0.2CuO4-xCe(0.9)Gd(0.1)O(1.95) (SCC-xCGO, x = 0-12 vol.%) composite cathodes supported on Ce0.9Gd0.1O1.95 (CGO) electrolyte are studied for applications in IT-SOFCs. Results show that Sm1.8Ce0.2CuO4 material is chemically compatible with Ce0.9Gd0.1O1.95 at 1000 degrees C. The composite electrode exhibits optimum microstructure and forms good contact with the electrolyte after sintering at 1000 degrees C for 4 h. The polarization resistance (R-p) reduces to the minimum value of 0.17 Omega cm(2) at 750 degrees C in air for SCC-CGO06 composite cathode. The relationship between R-p and oxygen partial pressure indicates that the reaction rate-limiting step is the surface diffusion of the dissociative adsorbed oxygen on the composite cathode. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.