The copper indium gallium diselenide Cu(In,Ga)Se-2 (CIGS) thin-films deposited on soda lime silica glass substrates were dip-coated five times and annealed at 180 degrees C. The advantages of CuIn(Ga)Se-2 thin films were its wide compositional tolerance, high conversion efficiency, flexibility, low cost of materials and high optical absorption in the visible spectrum. The effect of the withdrawal speed, on the optical properties of the CIGS thin films derived by sol-gel process detailed clearly in this study by transmission and reflection measurements with controlling the withdrawal speed. The prepared CIGS thin films had p-type conductivity. The significant blue shift of absorption edge as well as tuning of optical band gap was observed with the withdrawal speed. The CIGS thin films at four different withdrawal speeds were such as 60, 120, 200 and 300 mm min(-1) prepared from colloidal suspensions to control the nature of nanospheres in the CIGS texture, because the colloidal solution was utilised as a template to control the particle shape. (C) 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).