Thulium(III) nitrate is an inorganic compound, a salt of thulium and nitric acid with the chemical formula Tm(NO3)3.

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

[7] Both the compound and its crystalline hydrate decompose on moderate heating.

Thulium(III) nitrate hydrate is used as a reagent.

Also used in optical glasses, ceramics, catalysts, electrical components, and photo-optical materials.