Polycrystalline CdSe thin films (d = 0.08-1.65 µm) have been prepared by the quasi-closed volume technique under vacuum on glass substrates. The film structure was studied by the x-ray diffraction technique and atomic force microscopy. The values of the optical parameters (refractive index, n, and absorption coefficient, α) were determined from transmission spectra. The optical energy gap for the obtained CdSe films was also determined. The influence of deposition conditions (substrate temperature, evaporation source temperature) on the values of optical parameters is investigated.