Protactinium(IV) oxide

Protactinium(IV) oxide is a chemical compound with the formula PaO₂. The black oxide is formed by reducing Pa₂O₅ with hydrogen at 1 550 °C. Protactinium(IV) oxide does not dissolve in H₂SO₄, HNO₃, or HCl solutions, but reacts with the HF.

As protactinium(IV) oxide, like other protactinium compounds, is radioactive, toxic and very rare, it has no known technological use.