
Cadmium oxide (CdO) thin films have been deposited on glass substrate at R.T (300 K) by thermal oxidation with exist air. All samples were exposed to Gamma –Ray (γ – rays) source type (Cs 137) with energy (0.611MeV) for different irradiation time (2, 4 and 6) hours. In this study determines the effect of irradiation by (γ – rays) at different time on the structural, optical properties of as deposited films. X-ray techniques were used to characterize structural properties which indicate the formation of polycrystalline cubic CdO phase with preferential orientation along (111) plane. However, intensity of all peaks increases after irradiation which indicates that the crystallinity increases with increasing irradiation time. The transmission and absorptions spectrum of the films as a function of wavelengths in the range (300-1100) nm were used to study the optical properties before and after irradiation. The optical constants such as absorption coefficient, refractive index, extinction coefficient, real and imaginary parts of the dielectric constant and the electrical conductivity were investigated and calculated.