PbS nanocrystalline thin films were deposited on glass substrates using chemical bath technique at different solution temperatures and various deposition times. The thickness of the films was in the range 6001000 nm. The structure and the crystallite size of these films were studied by X-ray diffraction. The optical properties, absorption, transmission, and reflection, as a function of thickness were measured. The influence of thermal treatment under various annealing temperatures on the optical properties for some deposited films was studied and analyzed. (C) 2011 Elsevier B.V. All rights reserved.