Holmium (III) nitrate is an inorganic compound, a salt of holmium and nitric acid with the chemical formula Ho(NO3)3.

[2] Anhydrous salt is obtained by the action of nitrogen dioxide on holmium(III) oxide: Effect of nitrogen dioxide on metallic holmium: Reaction of holmium hydroxide and nitric acid: Holmium(III) nitrate forms yellowish crystals.

Forms a crystalline hydrate of the composition Ho(NO3)3•5H2O.

Hydrated holmitic nitrate thermally decomposes to form HoONO3 and decomposes to holmium oxide upon subsequent heating.

Also used to produce metallic holmium and as a chemical reagent.