(La0.6Sr0.4)(0.95)FeO3-delta/Sm0.2Ce0.8O2 (70:30, w/w) and (La0.6Sr0.4)(0.995)Co0.2Fe0.8O3-delta/Gd0.1Ce0.9O2 (50:50, w/w) cathodes screen printed on anode-supported cells were tested for 500h under different conditions by using a Taguchi matrix that combines cathode processing parameters (material composition, thickness, and sintering temperature) and operation conditions (temperature, current density, air flux, air humidification and chromium presence). Activation time increases with current density and varies with sintering temperature. Individual effect of each control factor on cell performance degradation was evaluated: chromium poisoning, air humidity and temperature were classified, in such order, as the most influencing parameters for cathode and cell degradation. Unexpected high degradation rates are reported at 750 degrees C. Limited influence of the type of cathode on long-term cells behavior is observed: LSF/SDC cathodes exhibits, however, higher long-term stability. (C) 2011 Elsevier Ltd. All rights reserved.