Erbium(III) selenide is an inorganic compound with a chemical formula of Er<sub>2</sub>Se<sub>3</sub>.
Erbium(III) selenide can be obtained by the reaction of erbium and selenium:
It can also be prepared by reacting erbium oxide and hydrogen selenide at high temperature.
Erbium(III) selenide is an orthorhombic crystal with a Sc<sub>2</sub>S<sub>3</sub> structure and a space group of Fddd. It reacts with magnesium selenide at 1000 ðC to obtain MgEr<sub>2</sub>Se<sub>4</sub>.