This paper reports the study of cobalt disulfide as a promising anode material for lithium ion batteries. The crystal structure and surface morphology have been characterized by using X-ray diffraction (XRD), SEM and Brunauer-Emmett-Teller (BET) techniques. The results of XRD show that the sample is a cubic phase with a space group Pa3. The grain size of the sample was 30 mu m with a special nano-structured characteristic as observed by means of SEM. Charge-discharge experiments show that the sample with 30 wt.% acetylene black at the current density of 50 mA g(-1) has the best performance, it shows that the first discharge capacity is up to 1280 mAh g(-1). Ex situ XRD experiments were also carried out to determine the structural changes of delithiated/lithiated anode materials and used to analyze the reaction mechanism. Calculated Gibbs free energy change (Delta rG) and electromotive force (emf, E) values for the reaction CoS2 + 4Li(+) + 4e(-) -> Co + 2Li(2)S are -146 kJ mol and 1.898 V, respectively. Based on the results, a possible reaction mechanism of CoS2 anode during intercalation of Li ions was proposed. (c) 2005 Elsevier B.V. All rights reserved.