We investigated the chemical bath deposition of CdS thin Rims on the Cu(In,Ga)Se-2 (CIGS) absorber layers and glasses. The process of the chemical bath deposition of CdS layer affected the performance of the CIGS solar cells. The CdS layers were deposited on the CIGS film from CdI2, thiourea (NH2CSNH2) and ammonia solutions. The influence of pH on the chemical bath deposition process was studied. The surfaces of the CdS films were observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The compositions of the obtained CdS layers were analyzed by Anger electron spectroscopy (AES). The performance of the CIGS solar cells was discussed on the basis of the characteristics of the chemical bath deposited layer. We have successfully fabricated a high-efficiency CIGS solar cell with an efficiency of 17% using a CdS layer with stoichiometric composition.