Thallium(III) oxide, also known as thallic oxide, is a chemical compound of thallium and oxygen.
It occurs in nature as the rare mineral avicennite.
Tl2O3 is metallic with high conductivity and is a degenerate n-type semiconductor which may have potential use in solar cells.
Contact with moisture and acids may form poisonous thallium compounds.
Alternatively, it can be created by the oxidation of thallium(I) nitrate by chlorine in an aqueous potassium hydroxide solution.