Regarding the electron transfer function of the intercuticular cement material (δ) and of the kerateine component (RK) of wool in the presence of cupric ion, cyclic voltammetry of aq. mixed solutions of methylviologen (MV) and various amino acid-cupric complexes were carried out on a bare carbon electrode. Cyclic voltammetry of MV aq. solution was also done using electrodes modified with δ-Cu2+ and RK-Cu2+. The occurrence of electron exchange between MV_??_ and cupric complex of basic amino acid (His and Arg) and of δ or RK was evidenced. These suggest that the electron transfer function of δ and RK results from the shift of the standard redox potential of Cu2+/Cu+ to more negative values by forming cupric complex with His and Arg residues in polypeptides of δ and that the cysteine residue in RK could also function as an electron carrier.