The optical characterization of amorphous and crystalline HfO2, SrHfO3, BaZrO3, BaHfO3, BaHf0.5Ti0.5O3, SrTiO3, Sr2Ta2O7 and Ta3Ti2Ox high dielectric constant thin (15-50 nm) films was performed using a combination of spectroscopic ellipsometry and reflectometry in the photon-energy range 1.5-6.8 eV. The optical dielectric function, absorption coefficient, optical band gap energies E-g. Urbach energy E-u and 3D interband critical point energies were obtained from these studies. The E-g as well as the E-u of the dielectric materials are important for device performance. Indirect E-g was obtained for all materials investigated. Lower E-g tends to result in higher value of permittivity kappa. The results obtained deliver the necessary information for the selection of alternative high-kappa dielectrics with adequate E-u, E-g and kappa values and additionally provide optical metrology for such films. (C) 2011 Elsevier B.V. All rights reserved.