Thulium(III) selenide is an inorganic compound with the chemical formula Tm2Se3.

Thulium(III) selenide can be obtained by the reaction of thulium and selenium:[3] It can also be prepared by reacting thulium oxide and hydrogen selenide at high temperature:[3] Thulium(III) selenide is also generated in the thermal decomposition of (py)3Tm(SePh)3.

[2] In the binary system of thulium(III) selenide and antimony triselenide, TmSb3Se6, Tm6Sb8Se21, TmSbSe3 and Tm8Sb2Se15 can be formed.

[4]