Terbium(IV) oxide is an inorganic compound with a chemical formula TbO<sub>2</sub>. It can be produced by oxidizing terbium(III) oxide by oxygen gas at 1000 atm and 300 ðC.
Terbium(IV) oxide starts to decompose at 340 ðC, producing Tb<sub>5</sub>O<sub>8</sub> and oxygen: