The electrochemical performances of Ag-(BaO)(0.11)(Bi2O3)(0.89) (BSB) composite cathodes on Ce0.8Sm0.2O1.9 electrolytes have been investigated for intermediate temperature solid oxide fuel cells (ITSOFCs) using ac impedance spectroscopy from 500 to 700 degrees C. Results indicate that the electrochemical properties of these composites are quite sensitive to the composition and the microstructure of the cathode. The optimum BSB addition (50% by volume) to Ag resulted in about 20 times lower area specific resistance (ASR) at 650 degrees C. The ASR values for the Ag50-BSB and Ag cathodes were 0.32 and 6.5 Omega cm(2) at 650 degrees C, respectively. The high performances of Ag-BSB cathodes are determined by the high catalytic activity for oxygen dissociation and ionic conductivity of BSB, and by the excellent catalytic activity for oxygen reduction of silver. The maximum power density of the Ag50-BSB cathode was 224 mWcm(-2) at 650 degrees C, which classify this composite as a promising material for ITSOFC. (C) 2007 Elsevier B.V. All rights reserved.