Cerium sulfide (CexSy) polycrystalline thin film is coated with chemical bath deposition on substrates (commercial glass). Transmittance, absorption, optical band gap and refractive index are examined by using UV/VIS. Spectrum. The hexagonal form is observed in the structural properties in XRD. The structural and optical properties of cerium sulfide thin films are analyzed at different pit. SEM and EDX analyses are made for surface analysis and elemental ratio in films. It is observed that some properties of films changed with different pH values. In this study, the focus is on the observed changes in the properties of films. The pH values were scanned at 6-10. The optical band gap changed with pH between 3.40 to 3.60 eV. In addition, the film thickness changed with pH at 411 nm to 880 nm. (C) 2014 Chinese Materials Research Society. Production and hosting by Elsevier B.V. All rights reserved.