Crystalline particles with a nanometric size and a cubic shape of CoSn3 have been prepared at a low temperature. The observed maximum reversible capacity in lithium test cells was 690 mAh g(-1). This capacity value is higher than that previously shown by other crystalline CoSnx intermetallic compounds with a lower tin content. The reaction of lithium with CoSn3 yields first to a lithium insertion into CoSn3 and second to the irreversible formation of a metallic glass, as studied using X-ray diffraction and Sn-119 Mossbauer spectroscopy. (C) 2008 The Electrochemical Society.