Transparent and polycrystalline zinc sulfide (ZnS) thin films were prepared by the chemical bath deposition (CBD) technique onto glass substrates deposited at 80 degrees C using aqueous solution of zinc acetate, thiourea, triethanolamine and tri-sodium citrate at a pH of about 10.55. Triethanolamine and tri-sodium citrate were used as complexing agents. The thickness of the films, which were calculated from the interference patterns around 400-800 nm maxima and minima wavelengths, varied from 403 to 934 nm in the visible range. UV-visible spectrophotometric measurement showed transperancy from 66% to 87% of the films with a direct allowed energy band gap in the range of 3.79-3.93 eV. X-ray diffraction (XRD) patterns prove crystallinity of deposited films that crystallize in the hexagonal phase of ZnS. The ZnS thin films were characterized by XRD, energy dispersive X-ray analysis (EDX) and optical absorption spectra. The current-voltage characteristic of polycrystalline ZnS films grown by CBD are reported. (c) 2006 Elsevier B.V. All rights reserved.