Abstarct: In this thesis, first zinc selenide (ZnSe) thin films were deposited onto glass substrates by the spray pyrolysis method using mixed aqueous solutions of ZnCl2 and SeO2. Then the effect of deposition temperature, solution flow rate, selenium dioxide molar ratio into zinc chloride, volume of the spray solution, annealing temperature and its time on the structural and optical properties of the films have been investigated. The X-ray diffraction (XRD) patterns indicate that the samples arepolycrystalline and have a cubic (zinc blende) structure. Investigation of deposition temperature effect indicates that the quality of crystal structure in sample prepared at 420 °C is better than the other two samples. Also the grain size in this temperature is increased. Study of solution flow rate effect, indicates that structure and surface morphology of sample prepared by rate of 6cc/min is better with respect to the other two samples. Study of Effect of selenium dioxide molar ratio into zinc chloride has no significant effect on the optical properties of the samples. Therefore, in this study, the molar ratio of 1:1 is used. Effect of temperature and time of annealing treatment on the physical properties of zinc selenide thin films show that the annealed sample at 60 min is higher quality than other specimens. The band gap value obtained for this sample is more agreement with other reports. Therefore, the appropriate annealing temperature and time, respectively, is 400C and 60 minutes. Investigation of annealing on physical properties of prepared samples with different deposition rates indicate that sample was prepared by rate of 6cc/min has better structural properties than sample prepared by rate of 4cc/min before and after annealing. However, the optical property of sample prepared by rate of 4cc/min is better. Effects of spray solution volume, as the effect of molar ratio, no significant changes on the structural and optical properties of the samples. The results show that some parameters such as deposition temperature, deposition rate, annealing temperature and its duration have considerable effects on the structural and optical properties of the films.