Neptunium(IV) nitrate is an inorganic compound, a salt of neptunium and nitric acid with the chemical formula Np(NO3)4.

[1][2][3] The compound forms gray crystals, dissolves in water, and forms crystal hydrates.

[4][5] Addition of dilute nitric acid to freshly prepared neptunium(IV) hydroxide:[6][7] Neptunium(IV) nitrate forms gray hygroscopic crystals.

It is soluble in water.

It forms a crystal hydrate of the composition Np(NO3)4•2H2O.