In this work, we report our results on the study of CdS thin films doped with fluorine (CdS:F) and oxygen (CdS:O) prepared by the RF-sputtering technique with CHF ₃ and O ₂ as reactive gases, respectively. XPS and XRD measurements showed that CdS:F is composed of CdS and CdF ₂ compounds, while CdS:O is composed of CdS, CdSO ₄ , CdSO ₃ and CdO ₂ . Both CdS:F and CdS:O samples are highly oriented along the (0 0 2) plane, but with less crystallinity than CdS film. Scanning electron microscopy images showed that the morphology is changed due to the presence of reactive gases. The optical transmittance in the short wavelength range ( λ < 500 nm) is improved in doped films, as higher values were achieved in CdS:O samples. By increasing the reactive gas concentration during the sputtering, the bandgap of CdS:O films is increased, while for CdS:F films it slightly decreases; in both kinds of samples, the refractive index is decreased and all doped films have higher electrical resistivity than CdS.