Results on the preparation and characterization of ZnSe epitaxial thin films obtained by electrodeposition on (111) and (100) n-type InP single-crystalline substrates, starting from elemental selenium dissolved in DMSO at 423 K, are reported. Voltammetric studies have been performed on these substrates and compared to SnO2:F covered glass substrates. They show substrate dependent behavior and the presence of parasitic faradaic reactions attributed to the formation of di-selenide anions. However, composition analysis of the films by electron dispersive spectroscopy revealed that, independent on the substrate, nearly stoichiometric ZnSe films are obtained within the deposition potential range. Scanning electron microscopy images present a specific effect of chloride ion on the films morphology, whereas their optical characterization showed a direct band gap value of 2.64 eV. The epitaxial quality of the deposits has been confirmed by reflection of high energy electron diffraction and atomic force microscopy techniques.