The high pressure transformation of rutile to TiO 2 -II with the α-PbO 2 structure is known to be kinetically hindered. In this study we show that a hydrothermal environment at 6GPa and 650°C provides appreciable rates for producing single phase bulk samples of TiO 2 -II. So obtained TiO 2 -II was characterized by scanning electron microscopy, powder X-ray diffraction, Raman and Far-IR spectroscopy. The structural properties are identical to TiO 2 -II from dry transitions. Transmission electron microscopy studies strongly indicate that Ostwald ripening processes play an important role in the hydrothermally assisted transformation and subsequent growth of TiO 2 -II crystals. TiO 2 -II is thermally stable to about 550°C. At 600°C the onset of the transformation to rutile is observed. The thermal expansion in the temperature range from room temperature to 500°C is highly anisotropic, virtually affecting only the c unit cell parameter (α c =7.1(2)×10 −6 °C −1 ). The pressure–temperature conditions for the hydrothermally assisted transformation of rutile are viable for industrial production settings, and in light of the large technological significance of TiO 2 , TiO 2 -II may present an interesting target for large-scale synthesis.