Phosphorus-doped nanosized TiO2 powders were prepared by a sol-gel technology. The optical absorption studies revealed that the spectral responses of phosphorus-doped (P-doped) TiO2 powders shift to the visible light region. The optimum phosphorus (P) content in our experiments is 16.7% (mol), and the corresponding absorption edge shifts to 450 nm. Furthermore, our ab initio calculations support the conclusion that the doping of phosphorus can reduce the band gap by mixing the P 3p states with O 2p states. The theoretical lattice parameters and optimum phosphorus content are in agreement with the experimental results. (C) 2009 Elsevier B. V. All rights reserved.