The structural, optical, and electronic properties of nitrogen doped TiO2 have been investigated experimentally and theoretically. The electronic and optical properties are investigated by using the first principles calculations in the framework of density functional theory and based on the full-potential linearized augmented plane wave method. The local density approximation plus on site Coulomb interaction was used for the exchange and correlation potential. The absorption and dielectric functions experimental data of as-grown sample show very good agreement with the theory. (C) 2011 Elsevier B.V. All rights reserved.