In this paper, the optical characterization of the NiO thin films prepared by pulsed laser deposition technique onto the quartz substrate were performed using multi-sample modification of the combined optical method based on measuring and interpreting the experimental data obtained by variable angle spectroscopic ellipsometry and spectrophotometry in reflected and transmitted light. A new dispersion model of the optical constants of the NiO films was also used. This dispersion model was based on parameterizing the joint density of states together with the Gaussian broadening. The defects consiting in boundary roughness and refractive index profile were taken into account in optical characterization of the NiO films too. The spectral dependences of the optical constants together with the parameters characterizing the defects of these films were determined. (c) 2004 Elsevier B.V. All rights reserved.