Titanium(III) oxide is the inorganic compound with the formula Ti<sub>2</sub>O<sub>3</sub>. A black semiconducting solid, it is prepared by reducing titanium dioxide with titanium metal at 1600 ðC.
Ti<sub>2</sub>O<sub>3</sub> adopts the Al<sub>2</sub>O<sub>3</sub> (corundum) structure. It is reactive with oxidising agents. At around 200 ðC, there is a transition from semiconducting to metallic conducting. Titanium(III) oxide occurs naturally as the extremely rare mineral in the form of tistarite. It is used as a catalyst for several reactions.
Other titanium(III) oxides include LiTi<sub>2</sub>O<sub>4</sub> and LiTiO<sub>2</sub>.