Neptunium(IV) fluoride or neptunium tetrafluoride is an inorganic compound with the formula NpF<sub>4</sub>. It is a green salt and is isostructural with UF<sub>4</sub>.
Neptunium(IV) fluoride can be prepared by reacting neptunium(III) fluoride or neptunium dioxide with a gas mixture of oxygen and hydrogen fluoride at 500 ðC:
It can also be prepared by treating neptunium dioxide with HF gas: