Neptunium(VII) oxide-hydroxide

This compound reacts with basic salts such as potassium hydroxide to form neptunates (NpO53-) and water.

[1] Neptunium(VII) oxide-hydroxide is stable in an alkaline solution, however, it is slowly reduced to Np(VI) in an acidic solution.

In water, it forms a greenish solution.

[1] This compound decomposes slowly to an oxidized solid.

[2] Neptunium(VII) oxide-hydroxide is produced by the oxidation of Np(VI) in alkaline solution with ozone, then neutralized with nitric acid to precipitate out the neptunium(VII) oxide-hydroxide.