Using Ti powder as reagent, TiO 2 nanoneedle/nanoribbon spheres were prepared via hydrothermal method in NaOH solution. The samples were characterized by field emission scanning electron microscopy （FESEM）, transmission electron microscopy （TEM） with selected area electron diffraction （SAED）, X-ray diffraction （XRD）, and UV-visible light absorption spectrum. The results indicate that the growth orientations of the crystals are influenced by the hydrothermal temperature and NaOH concentration. The diameter of the nanoneedle spheres and nanoribbon spheres （40 50 μm） are almost the same as that of Ti powders. TiO 2 nanoneedle/nanoribbon sphere powders are anatase after heat treatment at 450 °C for 1 h. Furthermore, methyl orange was used as a target molecule to estimate the photocatalytic activity of the specimens. Under the same testing conditions, the photocatalytic activities of the products decrease in the following order： TiO 2 nanoneedle sphere, TiO 2 nanoribbon sphere and P25.
