Polonium monoxide (also known as polonium(II) oxide) is a chemical compound with the formula . It is one of three oxides of polonium, the other two being polonium dioxide and polonium trioxide . It is an interchalcogen.
Polonium monoxide is a black solid. It is formed during the radiolysis of polonium sulfite and polonium selenite .
On contact with oxygen or water, both polonium monoxide and its related hydroxide (polonium(II) hydroxide,) are oxidized quickly to .