It is an ionic compound of nickel and fluorine and forms yellowish to green tetragonal crystals.

In fact, NiF2 comprises the passivating surface that forms on nickel alloys (e.g. monel) in the presence of hydrogen fluoride or elemental fluorine.

NiF2 is prepared by treatment of anhydrous nickel(II) chloride with fluorine at 350 °C:[2] The corresponding reaction of cobalt(II) chloride results in oxidation of the cobalt, whereas nickel remains in the +2 oxidation state after fluorination because its +3 oxidation state is less stable.

Like some other metal difluorides, NiF2 crystallizes in the rutile structure, which features octahedral Ni centers and planar fluorides.

[4] A melt of NiF2 and KF reacts to give successively potassium trifluoronickelate and potassium tetrafluoronickelate:[5] The structure of this material is closely related to some superconducting oxide materials.