Cobalt–tin intermetallic compounds with different particle size have been obtained and characterized by using 119Sn Mössbauer spectroscopy as a main tool. The electrochemical behavior of the Co–Sn compounds has been evaluated in lithium test cells. The Lamb–Mössbauer factors for CoSn with different crystallite sizes have been calculated. The results fnano − CoSn(300 K) = 0.19 and fcoarse − CoSn(300 K) = 0.55 are obtained. Nano-CoSn exhibits larger capacity to react with lithium than coarse-CoSn.