The preparation and subsequent oxidation of nickel cathodes modified by impregnation with zinc oxide (ZnO) were evaluated by surface and bulk analysis. The ZnO impregnated cathodes showed the similar porosity, pore size distribution and morphology as the reference nickel cathode. The stability tests of ZnO impregnated NiO cathodes in the eutectic molten Li/K carbonates showed that the ZnO additive could dramatically reduce the solubility of NiO in the melts under the standard cathode condition. The mechanism of ZnO additive on the solubility reduction of NiO cathode in the melts was also proposed in this paper. ZnO/NiO materials could be alternative cathode materials for molten carbonate fuel cells. (C) 2004 Published by Elsevier Ltd.