Polycrystalline thin films of ZnSxSe1-x with x = 0.0, 0.5 and 1.0 have been synthesised for the first time using a spray pyrolysis process. This process is based on the use of an aqueous solution of ZnCl2, thiourea and selenourea. The films were deposited onto glass substrates at different temperatures in the range, 250-550 degreesC, keeping the other deposition parameters constant and variations in the crystal structure, surface topography and optical properties investigated. Single phase layers of ZnSxSe1-x were produced for substrate temperatures of 350-500 degreesC. These layers had the wurzite crystal structure and consisted of densely packed grains. The films had optical transmittances > 75% for long wavelength photons and the absorption edges were found to be steep. The energy band gaps were found to vary in the range, 2.63-3.72 eV with a bowing parameter of 0.66 eV. (C) 2003 Elsevier Science B.V. All rights reserved.