Cadmium sulfide films of different thicknesses were deposited by chemical bath deposition (CBD) from a bath containing cadmium acetate, ammonium acetate, thiourea, and ammonium hydroxide. The XRD patterns show that the films are of hexagonal phase with preferred (002) orientation and the grain size increases with the thickness of the film. The band gap of the films was calculated from the transmittance data and it was found that the band gap decreases as the film grows in thickness. The photo-response studies indicate that the film thickness has an influence on the current decay under dark. The observed opto-electronic properties were attributed to the crystallite size and internal microstrain. (C) 2002 Elsevier Science B.V. All rights reserved.