Cd1-xErxS (x=0, 0.02, 0.04, 0.06, 0.08 and 0.10) thin films were produced by a chemical route on glass slides. The structural, morphological, optical and electrical properties of the grown samples were studied to obtain the optimum Er-doping level. Structural properties indicated that specimens had a hexagonal structure. Morphological analysis showed that the grain size of pristine CdS thin films remarkably reduced with rising Er-doping. The presence of Er atoms in CdS host structure was proved by energy dispersive of X-ray spectroscopy (EDS). The transparency of CdS thin films substantially improved after 10at.% Er-doping and a gradual decrease was acquired in the band gaps of the CdS samples with the increase of Er-doping. Photoluminescence data approved the existence of two main peaks corresponding to the green and yellow regions. Electrical properties of pristine CdS thin films were enhanced by Er-doping and the best electrical conclusions were obtained for Cd0.94Er0.06S thin films. Thus, it can be brought to an end that Er-doping enhanced both optical and electrical properties of pristine CdS thin films, which are of vital importance in optoelectronic applications.