The results of a comparative study of the optical properties of the thin films of zinc oxide ZnO, taking into account the influence of their copper doping, are presented. Using the experimental spectra of optical transmission, spectral dependences of the refractive and extinction index of the studied material, as well as components of complex dielectric permittivity constant, were calculated. The revealed features of the obtained dispersion curves are associated with the behavior of the impurity injected into the ZnO matrix. Keywords: zinc oxide, optical transmission, refractive index, dielectric permittivity.