Ternary Cd0.90Zn0.10S thin films of 0.0125M, 0.025M and 0.05M precursor concentrations have been successfully deposited on preheated (573 K) glass substrates using spray pyrolysis method. The structure, morphology and optical properties of depositshave been characterized by X-ray diffraction, scanning electron microscopy and UV–Visible spectrophotometry. X-ray diffraction study shows that the prepared films are polycrystalline with hexagonal wurtzite structure having preferred orientation along (0 0 2) plane. The crystallite size was increased with increasing molarity whereas, the dislocation density has reduced. The granular surface morphology was observed which was become more compact with increasing molarity. The optical transmittance and energy band gap was decreased with increasing molarity. [ABSTRACT FROM AUTHOR]