Abstract: Pure and doped CdS by 2.5, 5, 7.5 vol.% Li and Al thin films were prepared by chemical bath deposition method with thicknesses (150, 300, 450) "20 nm and annealed at 573 K for 1 h. X-ray diffraction analysis revels that pure and doped films crystallize in polycrystalline cubic structure with a preferred orientation along the 111 plane. The morphology of the films was studied by SEM and AFM. The surface morphology of CdS are best homogeneous and less pores after doping with Li and Al. UV-VIs spectra were obtained for the films before and after annealing. The values of optical transmittance and the optical energy gap of the films qualify them features to work as filters and antireflection coating to improve solar cell efficiency. The values of optical energy gap of pure and doped CdS by 2.5, 5, 7.5 vol.% Li and Al thin films were equal to (2.89, 2.81, 2.79, 2.72) eV and (2.89, 2.85, 2.79, 2.81) eV, respectively.