This study presents the woks on the electrochemical characterization and performance evaluation of using La0.75Sr0.25CUO2.5-delta (LSCu) as cathode material for intermediate temperature solid oxide fuel cell (IT-SOFC). The cell performance measurement was conducted on the Ni-YSZ anode supported single cell using the yittria-stabilized zirconia (YSZ) thin film (ca. 8 mu m) as electrolyte, and porous LSCu layer as cathode (ca. 80 mu m). The AC-impedance analyses were carried out by electrolyte supported LSCu/YSZ/Pt half-cell because of the thin YSZ film and the unsymmetrical between cathode and anode in the anode supported single cell may lose the accuracy. According to the analyses of the AC-impedance spectra, the spectra can be characterized by two arcs. The larger arc at low frequencies maybe attributed to the electrode polarization caused by the adsorption/desorption of the molecular oxygen, and the diffusion of oxygen ions. On the other hand, the much smaller one at high frequencies was attributed to the polarization during charge-transfer. The interface resistance was decreased by current passing. After 30 min of 200 mA cm(-2) current was passed, the overall resistance was decreased from 5.01 to 0.25 Omega. For the performance testing, the maximum power density at 800 degrees C is 0.65 W CM-2 with 150 and 500 sccm of hydrogen and air flows, respectively. According to these results, LSCu is a potential cathode material for the IT-SOFC. (c) 2005 Elsevier B.V All rights reserved.