Polycrystalline Dy thin films, coated with a very thin Pd layer, have been deposited on glass substrates by electron beam evaporation and subsequently hydrided. For hydrogen partial pressures larger than 0.7 kPa, a semiconductor character is displayed in the optical properties of the DyH2+x thin films. A parametric model is applied to follow the evolution with hydrogen pressure of various parameters characterizing the absorption by the semiconductor DyH2+x thin films. The contribution of the free electrons to the absorption of light is also considered within a Drude model incorporating the presence of the hydrogen atoms as ionized impurity scattering centers. (c) 2007 Elsevier B.V. All rights reserved.