This study aims to deposit different thicknesses of CdS thin films with a variation of deposition time by using chemical bath deposition technique. The aqueous solution of cadmium chloride, ammonium chloride, ammonium hydroxide and thiourea were used During the deposition process. The analysis was done to observe the effect of annealing on structural, optical and electrical properties of the CdS thin films. From the x‐ray diffraction, this helps to confirm the cubic CdS phase formation, with a preferred orientation along (111). The finding indicates that the crystallite size is larger in films when it is deposited with low deposition rate. The crystallite size increased with increasing thickness and decreased after annealing. After annealing, the mobility and carrier concentration of the CdS thin films of different thicknesses is increasing and the resistivity decreasing. This study showed that the crystal structure, band gap, Urbach energy and electrical properties of CdS thin films can be changed when Cds thin films experienced annealing.