The main barrier to symmetrical solid oxide fuel cells (SOFCs), where the same catalytic materials are used simultaneously as the anodes and the cathodes, is to identify a redox-stable catalyst that exhibits superior catalytic activities for both fuel oxidation and oxygen reduction reactions. Here we report a Sc-substituted La0.6Sr0.4FeO3-delta oxide, La0.6Sr0.4Fe0.9Sc0.1O3-delta, that shows great promise as a new symmetrical electrode material with good structural stability and reasonable conductivities in air and hydrogen. We further demonstrate that nano-scale La0.6Sr0.4Fe0.9Sc0.1O3-delta catalysts impregnated into the porous La0.9Sr0.1Ga0.8Mg0.2O3-delta backbones exhibit good catalytic activities for oxygen reduction and hydrogen oxidation reactions and thereby yield low polarization resistances, e.g., 0.015 Omega cm(2) in air and 0.29 Omega cm(2) in hydrogen with appropriate current collection at 800 degrees C. Thin La0.9Sr0.1Ga0.8Mg0.2O3-delta electrolyte fuel cells with such symmetrical La0.6Sr0.4Fe0.9Sc0.1O3-delta catalysts showed maximum power densities of 0.56 and 0.32 W cm(-2) when operating on 97% H-2-3% H2O at 800 and 700 degrees C, respectively. (C) 2013 Elsevier B.V. All rights reserved.