The effect of FeS and PbS on capacity and self-discharge of an iron porous electrode used in a Fe-Ni battery was investigated. Addition of I wt.% FeS or I wt.% PbS promotes a significant increase in capacity and inhibits the self-discharge of the iron electrode. This effect is most significant in the presence of PbS. (C) 2004 Elsevier B.V. All rights reserved.