Lanthanum nickelate (LN, La2NiO4-delta) is a mixed ionic and electronic conductor with oxygen self-diffusion and surface exchange properties that predict that it will be a good cathode catalyst for solid oxide fuel cells. We show that LN performs poorly (0.3 W cm(-2)) when used as a single-phase cathode in yttria-stabilized-zirconia-based air-H-2 dime cells at 800 degrees C. Power densities up to 2.2 W cm(-2) are measured only when LN is used in a composite bilayer cathode. Parametric modeling shows that the kinetics of the LN-based cathodes is relatively poor, but their low ohmic resistance leads to their high power density. (C) 2007 The Electrochemical Society.