In the present paper, we have studied size and dimension effect on diffusion coefficient of nitrogen and platinum doped TiO(2) nanoparticle using Arrhenius relation and Lindeman's criteria under their dynamic limit. The activation energy and melting point decreases with decrease in size. The TiO2 diffused with metal and nonmetal gives rise to (meta-) stable structure and mid-gap state helps to increase surface to volume ratio and quantum confinement effects, and results in the increase of diffusion coefficient. The calculated diffusion coefficient of undiffused TiO(2) with size is in good agreement with available experimental data. (C) 2010 Elsevier B.V. All rights reserved.