Anatase TiO2 crystallites have been prepared by hydrothermal homogeneous precipitation from Ti(SO4)(2) aqueous solution with urea without using any additives. The structural evolution with the calcination temperature of the photocatalyst was studied. The photocatalytic activity of the obtained photocatalysts was investigated using X-3B dye as a model pollutant. The as-prepared anatase TiO2 crystallites were highly resistant to thermal sintering, and the calcinations up to 800 degrees C were shown to enhance the crystallinity of the anatase phase without any rutile phase, which is attributed to the protection of traces of sulfate ions that are produced during the precipitation of titanium sulfate. The gradually increased photocatalytic activity of the anatase TiO2 calcined from 110 to 800 degrees C demonstrated strong dependency on its crystallinity. The anatase TiO2 calcined at 800 degrees C afforded the highest photocatalytic activity, which was obviously higher than that of commercial Degussa P25 on the photodegradation of X-3B dye in water under ultraviolet light irradiation, and exhibits much faster sedimentability. (C) 2013 Elsevier B.V. All rights reserved.