A study of the cathode properties of an intermediate temperature-operating solid oxide fuel cell (IT-SOFC) was carried out using La0.8Sr0.2Co1-x MnxO3-delta (LSCM). LSCM-8246 had the lowest impedance on the 8 mol% yttria-stabilized zirconia (YSZ) electrolyte among the various compositions investigated in this study. A Ce0.9Gd0.1O2-delta (CGO) interlayer between LSCM and YSZ was introduced to inhibit the fori-nation of resistive phases. Cathode impedance was decreased by approximately three times compared to that shown with non-interlayer samples. Investigation of the oxygen partial pressure dependence of LSCM-8246 on CGO-layered YSZ showed that the adsorbed oxygen ionization is the rate-determining step of the cathode reaction. The cathode material and structure can be applied to IT-SOFC at 700 degrees C because the area-specific resistance is sufficiently low, leading to a cell power density higher than 0.5 W/cm(2) at 0.7 V. (C) 2008 Elsevier B.V. All rights reserved.