TiO2 nanoparticles were prepared by direct hydrolysis method from metatitanic acid. After the resulting powders were peptized by hydrochloric acid, the results showed that peptization of the precipitate favored formation of the rutile phase and highly crystalline anatase. Particles of the 100% rutile phase with high specific surface areas were obtained at relatively low temperatures. The specimens were characterized by transmission electron microscopy (TEM), X-ray diffractometry, Brunauer-Emmitt-Teller (BET) surface area analysis, and differential thermal analysis. To evaluate the effects of different phases on the degradation efficiency, anatase/rutile mixtures exhibited the best catalytic efficiency for the degradation of sodium benzenesulfate (BS), while pure rutile was the poorest catalyst.