Thin films of CuI were prepared by different techniques and their characteristics were studied. A remarkable blue shift in the onset of the optical absorption of thin CuI films is observed compared to that of polycrystalline CuI. These films exhibited an optical transmittance of over 80% in the wavelength range 400-900 nm. The conductivity and the intensity of cathodoluminance of the films vary with deposition technique. Different mechanisms are proposed for the luminescence at different wavelengths. (C) 2003 Elsevier Science B.V. All rights reserved.