A cathode-supported SOFC consisting of LSM (La(0.8)Sra(0.2)MnO(3-delta)) cathode supporter, LSM-Sm0.2Ce0.8O2-delta (SDC) cathode functional layer (CFL), yttria stabilized zirconia (YSZ)/SDC bi-layered electrolyte and Ni-YSZ anode layer was fabricated by a slurry spin coating technique. The influence of the porosity in both the CFL and cathode supporter on the electrochemical properties of the cells has been investigated. It was found that properly controlling the porosity in the CFL would improve the performance of the cells using 02 in the cathode side (O-2-cells), with a maximum power density (MPD) value achieving as high as 0.58 W cm(-2) at 850 degrees C. However, this improvement is not so evident for the cells using air in the cathode side (air-cells). When increasing the porosity in the cathode-supporter, a significant increase of the power density for the air cells due to the decreasing R-conc,R-c (cathode concentration polarization to the cell resistance) can be ascertained. In terms of our analysis on various electrochemical parameters, the R-act (activation polarization to the cell resistance) is assumed to be mainly responsible for the impedance arcs measured under the OCV condition, with a negligible R-conc,R-c value being able to be detected in our impedances. In this case, a significant decreasing size of the impedance arcs due to the increasing porosity in the cathode supporter would correspond to a decrease of the R-act values, which was proved to be induced by the decreasing R-conc,R-c. (C) 2012 Elsevier Ltd. All rights reserved.