A kind of composite cathode, La0.58Sr0.4Co0.2Fe0.8O3-delta-Ce0.8Sm0.2O2-delta (LSCF-SDC), was presented in this paper. The electrochemical performance of the cathode on the electrolyte of SDC and YSZ coated with a thin SDC (YSZ/SDC) layer was studied by electrochemical impedance spectroscopy (EIS) and cathodic polarization techniques for their potential utilization in the intermediate temperature solid oxide fuel cell (IT-SOFQ. Also studied was the relationship between the electro-catalytic characteristics and the electrode microstructure. Results showed that the LSCF-SDC composite electrode performed better on the SDC electrolyte than on the electrolyte of YSZ/SDC. The polarization resistance, RP, of the cathode on the SDC electrolyte was 0.23 ohm cm(2) at 700 degrees C and 0.067 ohm cm(2) at 750 degrees C, much lower than the corresponding R-p of the same cathode on the YSZ/SDC electrolyte. At 750 degrees C, the cathodic overpotential of the composite cathode on the SDC electrolyte was 99.7 mV at the current density of 1.0 A cm(-2). (c) 2007 Elsevier Ltd. All rights reserved.