Neptunium(V) fluoride or neptunium pentafluoride is a chemical compound of neptunium and fluorine with the formula NpF5.
Neptunium(V) fluoride can be prepared by reacting neptunium(VI) fluoride with iodine:
| 10 NpF6 + I2 \longrightarrow 10 NpF5 + 2 IF5 |
From the equation above, iodine pentafluoride is a byproduct.
Neptunium(V) fluoride thermally decomposes at 318 °C to produce neptunium(IV) fluoride and neptunium(VI) fluoride. Contrary to uranium(V) fluoride, neptunium(V) fluoride does not react with boron trichloride, but it reacts with lithium fluoride in anhydrous HF to produce LiNpF6.