Cadmium selenide (CdSe) films were prepared by hot wall deposition technique using optimized tube length under a vacuum of 6 mPa on to well-cleaned glass and ITO substrates. The X-ray diffraction analysis revealed that the films are polycrystalline in nature for lower thickness and at lower substrate temperatures, but with increasing thickness and increasing substrate temperature a more preferred orientation along (0 0 2) direction was observed. The crystallite size (D), dislocation density (delta) and strain (epsilon) were calculated. An analysis of optical measurements revealed a sharp absorption around 700 nm and a direct allowed transition. The band gap was found to be around 1.7 ev. The effect of thickness and substrate temperature on the fundamental optical parameters like band gap, refractive index and extinction coefficient are studied. (C) 2002 Elsevier Science B.V. All rights reserved.