Cd1-xZnxS films with low Zn content were obtained on glass substrates by an ammonia-free chemical bath deposition process. Alkaline reaction solutions were prepared using cadmium chloride, zinc chloride, sodium citrate, thiourea and potassium hydroxide. As a result of varying the mixture ratio between Cd and Zn precursors, microstructural studies from X-ray diffraction reveal that the resulting films have hexagonal, wurzite type, crystalline structure with changes in the preferential growth orientation. Important changes on the surface morphology and thickness of the Cd1-xZnxS films were also observed as effects of adding Zn to the CdS lattice. Optical studies show that Cd1-xZnxS thin films with energy band gaps in the range from 2.48 to 2.65 eV were obtained. (C) 2013 Elsevier B. V. All rights reserved.