The electrochemical characteristics of the solid oxide fuel cell (SOFC) cathodes prepared by infiltration of (La0.85Sr0.15)(0.9)MnO3-delta (LSM) nanoparticles into porous Y0.5Bi1.5O3 (YSB) backbones are investigated in terms of overpotential, interfacial polarization resistance, and single cell performance obtained with three-electrode cell, symmetrical cell, and single cell, respectively. X-ray diffraction confirms the formation of perovskite LSM by heating the infiltrated nitrates at 800 degrees C. The electrical conductivity of the electrode measured using Van der Pauw method is 1.67 S cm(-1), which is acceptable at the typical SOFC operating temperatures. The single cell with the LSM infiltrated YSB cathode generates maximum power densities of 0.23, 0.45, 0.78, and 1.13W cm(-2) at 600, 650, 700, and 750 degrees C, respectively. The oxygen reduction mechanism on the cathode is studied by analyzing the impedance spectra obtained under various temperatures and oxygen partial pressures. The impedance spectra under various cathodic current densities are also measured to study the effect of cathodic polarization on the performance of the cathode. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.