A nano-structured Sm0.5Sr0.5CoO3 (- delta) (SSC) cathode is fabricated by an ion-impregnation method for intermediate-temperature SOFCs based on zirconia electrolytes. X-ray diffraction analysis shows that perovskite SSC is formed when the impregnated nitrates are fired at 800 degrees C for 1 h. Scanning electron microscopy reveals that the SSC particles are nano-structured. The effect of the electrode thickness, the amount of SSC loading, and the firing process on the interfacial polarization resistance are investigated using symmetrical cells. Anode-supported cells with the nano-structured cathode show an interfacial polarization resistance of only 029 Omega cm(2) at 600 degrees C and produce a peak power density of 437 mW/cm(2) at 600 degrees C with humidified hydrogen as the fuel. The high cell performance indicates that SSC nanoparticle impregnated samaria-doped ceria electrodes are promising for intermediate-temperature SOFCs. (C) 2010 Elsevier B.V. All rights reserved.