A three-dimensional (3D) titanium dioxide nanostructure consisting of a nanoparticle core and needlelike surface was fabricated. The effects of Ti4+ concentration, stirring methods and stirring time for TiO2 preparation were discussed with results from transmission and scanning electron microscopy; meanwhile, the TiO2 growth mechanism was illustrated by morphology evolution and crystallization of titanium dioxide spheres. The spherical diameter could be easily controlled by altering the concentration of precursor using a mechanical stirring method. X-ray photoelectron spectroscopy, Fourier transform infrared spectrometry and thermogravimetric analysis were used to confirm the composition of titanium dioxide spheres rich with hydroxyl groups. The product showed excellent ability for arsenic(V) and chromium(VI) removal and could be separated using sedimentation. Most of the ions could be removed in less than 1 h, and TiO2 had maximum adsorption capacities of 59.7 mg g(-1) for arsenic(V) and 21.92 mg g(-1) for chromium(VI). The high performance of self-assembled 3D titanium dioxide in water treatment was due to (1) its large hydroxyl group density and high specific surface area and (2) its 3D nanostructure consisting of a nanoparticle core and needlelike surface. (C) 2013 Elsevier B.V. All rights reserved.