Nanosized Sn-Cu-B alloy powder is synthesized by chemical reduction to be used as an alternative anode material for secondary lithium batteries. The alloy powder consists of two phases, i.e. mainly eta'-Cu6Sn5 and a small amount of epsilon-Cu3Sn. The reaction of Cu6Sn5 with lithium proceeds in two steps. Lithium is inserted into the Cu6Sn5 lattice first as LixCu6Sn5, which is isostructural with Li2CuSn, followed by alloying with tin, reversibly even after long cycling. The cycle performance of the nanosized Cu6Sn5 electrode is significantly enhanced in comparison with that of the same material prepared by sintering or mechanical alloying.