SnS films have been grown by spray pyrolysis technique on Coming 7059 glass substrates at different substrate temperatures that vary in the range of 100-450 degrees C, keeping the other deposition parameters constant. The optical properties of the films were systematically studied using the optical transmittance and reflectance data. The optical absorption coefficient and optical energy band gap of the films were evaluated. The variation of refractive index and extinction coefficient with photon energy for the films grown at different temperatures were studied. The SnS films grown at the substrate temperature range 300-375 degrees C, were showed an absorption coefficient > 10(4) cm(-1) with the energy band gap 1.32 eV, measured at room temperature. For these films, the material properties such as the dielectric constants (n, n(0), k, epsilon(0) and epsilon(infinity)), plasma frequency (omega(p)), hole effective mass (m(h)*) and carrier density (N-opt) were also evaluated. (c) 2005 Elsevier Ltd. All rights reserved.