A stable aqueous electrolyte solution containing Cu(II) cations and (S CN) anions was prepared by adding EDTA(ethylenediamine tetraacetic acid disodiu m salt, C10H14N2O8Na2·2H2O) to chelate with Cu(II) cations. CuSCN films were el ectrodeposited on transparent ITO conducting substrates from as-prepared electro lyte solution. Deposition mechanisms of CuSCN at varied temperatures have been s tudied. The results indicate that electron quantum tunnel through CuSCN film pla ys a role and the dense thin film with nanocrystals was obtained at or below roo m temperature. However, at higher temperature, a thermally activated process was involved and a thick film was obtained. It has been calculated that the activat ion energy of the growth for crystals is 0.5 eV. XPS pattern shows that the elec trodeposited film is (SCN) in stoichiometric excess, indicating a p-type film. A s-prepared CuSCN film was with high transmittance (≥85%) in the visible optical range and the direct transition band gap was 3.7 eV.