La1-xSrxCuO2.5-delta (LSCu), which exhibit excellent electrical conductivity and oxygen vacancies were investigated as potential cathode materials for solid oxide fuel cell (SOFC) applications. The structure stability, electrical conductivity, cathodic overpotential, and the reactivity with yttria-stabilized zirconia (YSZ) were examined in this study. It was found that the LSCu perovskite was obtained only When the addition of strontium fell in the range between 15 and 30%. With more than 20% of strontium addition, this material showed excellent electrical property and immunity to the reaction with YSZ at 800 degreesC. The conductivities of LSCu were as high as 900 S/cm at 600 degreesC, and 800 S/cm, at 800 degreesC. The cathodic overpotential of this material was approximately 18 and 10.6 mV at a current density of 100 mA/cm(2) at 850 and 750 degreesC, respectively. These properties are superior to Sr-doped lanthanum manganite (LSM), which is the state-of-the-art cathode material of SOFCs. (C) 2002 Elsevier Science Ltd. All rights reserved.