Two types of nanosize intermetallic alloy powders. NiSi and FeSi, are prepared by high-energy ball-milling. The alloys are used as electrode materials in lithium test cells. During lithium insertion into the alloy electrodes, Si acts as active centres, which react with Li to form LixSi alloys. A high lithium storage capacity of 1180 mA h g(-1) is observed for the NiSi electrode, with some reversibility. A mechanism for the reaction of NiSi and FeSi with Li+ is proposed. (C) 2000 Elsevier Science S.A. All rights reserved.