The effects of TiO2 on the band structure and the crystallinity of the HfO2 were studied. The bandgap energy decreases by increasing TiO2 concentration. The shift in the valence band edge and the conduction band edge are due to the changes in electronic band structures and in microstructure. First principle calculations were carried out on the electronic band structures. Our experimental results confirmed the theoretical studies. (C) 2010 Elsevier B.V. All rights reserved.