The voltammetric methods were used to prove the interaction of metal complex Co(phen)33+ with bovine serum albumin (BSA). The interaction of BSA with Co(phen)33+ molecules using BSA-modified electrode is described. Information of the binding ratio and interaction mode can be obtained from their electrochemical behavior and electrochemical data. Furthermore, attenuated total reflection infrared experiment was performed to prove the interaction between complexes and BSA.