Erbium(III) nitrate is an inorganic compound, a salt of erbium and nitric acid with the chemical formula Er(NO3)3.

[4][5] Dissolving metallic erbium in nitric acid: Dissolving erbium oxide or hydroxide in nitric acid: Reaction of nitrogen dioxide with metallic erbium: Erbium(III) nitrate forms pink hygroscopic crystals.

Forms crystalline hydrates of the composition Er(NO3)3·5H2O.

Both erbium(III) nitrate and its crystalline hydrate decompose on heating.

It is used to obtain metallic erbium and is also used as a chemical reagent.