Visible light response and superior dispersed S6+-doped TiO2 nanoparticle catalysts (S-TiO2) were prepared via ionic liquid of 1-butyl-3-methylimidazolium hexafluorophosphate. The phenol was used for the evaluation of the S-TiO2 photocatalytic activity. S-TiO2 was characterized by XPS, UV-vis DRS, FESEM, TEM, XRD, TG/DSC, FTIR, and BET. The results showed that S-TiO2 with appropriate S doping prepared via ionic liquid had smaller particle size, better dispersion, higher activity, and higher surface area (SBET) than that prepared in water. Cationic S6+ incorporation into TiO2 lattice substitutes for Ti4+ lattice site, generates Ti-O-S bonds in TiO2, and leads to the formation of donor defect levels in band gap, so that the photocatalytic sensitization of TiO2 has been extended to visible light region. The optimal content in S doping for the better photocatalytic performance can optimize electrical properties of the intrinsic n-type TiO2 by adding the adequate amount of donor defect of STi2+ for considering the lifetime of the photoinduced charge pairs. (C) 2017 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.