An accurate characterization method is developed to determine the refractive index of smooth and surface-textured transparent conductive oxide (TCOs) films. The properties are obtained from simultaneous fitting of simulated specular reflectance/transmittance spectra to spectroscopic measurements for different polarizations and angles of light incidence. The simulations are based on a combination of physical models describing dielectric function of TCO films. Besides the refractive index also other material properties of TCO films are obtained, such as the band gap and free carrier absorption. A light scattering model is implemented into the simulations to take into account the diffused part of the light scattered at randomly-textured surfaces of TCO films.@en