The electrochemical property of C70 films was studied by cyclic voltammetry and electrochemical quartz crystal microbalance in organic electrolyte solution. The electrochemical behavior of C70 film shows that both formation of solvent separated ion pair in monoanion C70 state and formation of contact ion pair in dianion C70 state were observed. Mechanisms of these processes which involved film swelling with solvent and intercalation of cations into film were proposed. Tetramethylammonium perchlorate was used as supporting electrolyte in acetonitrile solution. Thin films of C70 were prepared by solvent evaporation method on hot glassy carbon electrode.