The optical response of vacuum-evaporated Cd1-xZnxTe thin films in the 1.5-5.6 eV photon energy range at room temperature has been studied by spectroscopic ellipsometry. The films of Cd1-xZnxTe (x=0.04) were deposited at room temperature onto well-cleaned glass substrates of film thickness 450 nm. The measured dielectric-function spectra reveal distinct structures at energies of the E-1, E-1+Delta(1) and E-2 critical points corresponding to the interband transitions. Dielectric related optical constants such as complex refractive index, the absorption coefficients and the normal incidence reflectivity, are presented. Results are in satisfactory agreement with the calculations over the entire range of the photon energies.