The chemical bath deposition (CBD) technique was used for PbS-CdS thin films synthesis, on glass substrates, in an alkaline solution. This heterostructure of firmly adhered films is useful for solar absorbers, solar device control, and other important applications. The reactive substances used to obtain the PbS layers were lead acetate and thiourea whereas the substances to obtain the CdS layers were cadmium chloride and thiourea. The PbS layers of 40 nm in thickness were grown at room temperature during 75 min. Different CdS layers were grown at constant temperatures in the range 30-80 degrees C, during 30, 60 and 90 min in each case. The two-layers system was characterized by X-ray diffraction, scanning electron microscopy, and optical absorption measurements. The formation of CdS clusters on the films' surface was studied as a function of the reaction temperature.