The skutterudite-type CoSb3 alloy was prepared using levitation melting. The electrochemical properties of CoSb3 were investigated using Li ion model cells, Li/LiPF6(EC+DMC)/CoSb3. It was found that the first reversible capacity is about 420 mA h g−1. Ex-situ XRD (X-ray diffraction) experiments have been used to characterize the electrochemical lithiation and de-lithiation mechanism of CoSb3 alloy. The results revealed that when CoSb3 is intercalated by Li ions, it decomposes into Co and Sb first, followed by the formation of the Li3Sb phase, which is dispersed in the Co matrix. When Li ions are removed from Li3Sb, Co and Sb atoms cannot reconstruct CoSb3, while the Li–Sb alloying and de-alloying processes are reversible.