Optical properties and microstructure of Ca0.4Sm0.4TiO3 thin films prepared by sol-gel method on glass substrate at different preheating and annealing treatments have been investigated. The diffraction pattern showed that the deposited films exhibited a polycrystalline microstructure. All films exhibited Ca0.4Sm0.4TiO3 peaks orientation perpendicular to the substrate surface and the grain size with the increase in the preheating and annealing temperature. Optical transmittance spectroscopy further revealed high transparency (over 80%) in the visible region of the spectrum. The dependence of the physical and optical characteristics on various preheating and annealing treatments was also investigated. (C) 2013 Elsevier B.V. All rights reserved.