The polarization loss due to oxygen reduction at the cathode in solid oxide fuel cells is a thermally activated process; therefore, as temperature is lowered, the loss becomes substantial. Highly active cathodes have been investigated by several groups; equally important, if not more, is the stability of these electrodes. The high performance and stable Pr2NiO4 cathode was studied by impedance spectroscopy and dc current-potential sweeping methods. The power density in Pr2NiO4-based anode supported button cells was in the range between 0.65 and 0.7 W/cm(2) at 750 degrees C at the external load of 0.8 V. The degradation rate at 0.8 V was approximately 3% per 1000 h up to 2000 h. The electrode resistance is a function of external loads, thus also varies with current densities. The relationship between electrode resistance and external loads is non-linear, which may changes in lattice oxygen nonstoichiometry of the cathodes. (C) 2012 Elsevier Ltd. All rights reserved.