Nanostructured La1-alpha SraCo1-bFebO3-x (a = 0.3 - 0.5; b = 0 - 0.2 ) and Ce0.8Sm0.2O2 powders were successfully prepared by citrate-nitrate autocombustion synthesis and were characterized by scanning electron microscopy and X-ray diffraction analysis. Electrochemical impedance spectroscopy measurements on symmetric cells were performed to evaluate the applicability of La1-aSraCo1-bFebO3-x as a cathode material for intermediate temperature solid oxide fuel cells based on Sm doped-ceria electrolytes. Our results demonstrated that strontium has a positive effect while iron shows a slightly negative effect on the interfacial resistance. The effect of the electrode sintering temperature was investigated by varying the temperature from 850 to 1250 degrees C, and the best sintering temperature was found to be 900 degrees C. The best characteristics as cathode at intermediate operating temperatures were found for the composition with a = 0.4 and the minimum iron doping, b = 0.05; at 700 degrees C, an area specific resistance of 0.13 Omega cm(2) was measured. (c) 2006 The Electrochemical Society.