In this study, Cu x Zn 1-x S (where x= 0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1) thin films have been successfully deposited on glass substrates by chemical spray pyrolysis (CSP) technique at substrate temperature of (400 o C). The thickness of the prepared thin films was about (350 ± 30) nm measured by gravimetric method. Various characterization techniques have been used to investigate the structural and optical properties of the prepared thin films. The XRD results showed that the CuS film has a polycrystalline nature with covellite-hexagonal structure and preferred orientation along (103) plane, and the ZnS film has a polycrystalline wurtzite-hexagonal structure with preferred orientation along (0010) plane, while the thin films prepared with different mixing ratios have a polycrystalline structure and mixture phases of covellite-hexagonal and wurtzite-hexagonal. AFM results showed homogenous and smooth thin films. FESEM results showed the formation nanostructures with different shapes, such as cauliflower, semi-spherical, hexagonal, and in the form of plates and rods. The UV-Visible-NIR absorbance spectra were recorded in the range of (350-900) nm to investigate the optical characteristics. The results have shown that the transmittance of the prepared thin films decreases with increasing the CuS ratio and the absorption coefficient value is (α >10 4 cm-1) for all prepared thin films, which this in turn proved that the prepared thin films are likely to have direct electronic transitions. It is found that the optical energy gap decreases with increasing the CuS ratio, and it is in the range of (2.12-3.34) eV.