In this paper, Ce0.8Sm0.2O1.9 (SDC) nanoparticles modified GdBaCo2O5+delta (GBCO) cathodes were fabricated by an infiltration technique and evaluated for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Good chemical compatibility between GBCO and infiltrated SDC was confirmed by X-ray diffraction (XRD) characterization. SDC nanoparticles (similar to 40 nm) formed continuous ionic-conducting phase on porous GBCO backbone, which contributed to significantly improved electro-catalytic property. At 600 degrees C, the composite cathode with 3.3 mg cm(-2) SDC loading exhibited encouragingly low R, value of 0.1 Omega cm(2), which was much lower than 0.43 Omega cm(2) of pure-GBCO cathode. As revealed by PO2 dependence of impedance spectra, the oxygen reduction reaction was mainly limited by charge-transfer processes. Furthermore, a stable operation of 80 h was obtained at 600 degrees C. Our study implies that infiltrated GBCO cathode is very attractive for application in IT-SOFC cathode. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.