The electrochemical behavior of 4-methylesculetin-boric acid complex (4MS-B) in aqueous solution has been studied at a glassy carbon electrode using cyclic voltammetry. The results indicate that 4MS-B is involved in the CE mechanism. In the next step the electrochemical oxidation of 4-methylesculetin (4MS) was studied in the presence of glutathione using cyclic voltammetry. The results indicate a complicated catalytic system. Finally the electrochemical behavior of 4MS-B in the presence of glutathione has been studied using cyclic voltammetry as a diagnostic technique. The results indicate that this system is involved in the CEC' process as a new electrochemical mechanism. In this work, the impact of empirical parameters on the shape of the voltammograms is examined based on a CEC mechanism. (c) 2013 Elsevier Ltd. All rights reserved.