This paper demonstrates Li2O/M and Li2S/M (M = Co, Fe) composites that contain electrochemically active lithium. The composites were made by ballmilling Li2O or Li2S with metal powder. The resulting materials had average grain sizes of similar to100 Angstrom and enormous reversible capacities of up to 600 mAh/g. When cycled within appropriate voltage limits, the electrodes showed no capacity fading. These composites are compatible with lithium-ion technology and could provide a safe, high-energy density alternative to conventional intercalation electrodes. (C) 2002 The Electrochemical Society.