The optical transmission spectra of amorphous (a-) Se-1 In-x(x) films, with x = 0.0, 0.05, 0.18 and 0.35, that prepared by thermal evaporation from their corresponding bulk ingots, are recorded over the spectral region of 500-2500 nm. A simple straight forward procedure proposed by Swanepeol has been applied to determine the two components of the complex refractive index ((n) over tilde). The dispersion of (n) over tilde is examined in terms of the Wemple and DiDomenico model and is discussed in terms of In-content. An estimation of various optical parameters such as, the optical energy gap (E-g = 1.96-1.33 eV), single oscillator energy (E-o = 3.95-3.16 eV), oscillator dispersion energy (E-d = 22.6-31.6 eV), lattice oscillator strength (E-l = 0.38-0.61 eV) and wavelength at zero material dispersion (lambda(c) = 2.0569-2.0879 mu m) have been given and discussed in relation to the coordination number, hydrostatic density and formed chemical bonds that are introduced in the network of a- Se with the introduction of up to 35 at.% In. (C) 2009 Elsevier B. V. All rights reserved.