[4] It exothermically reacts with water to produce oxonium hexafluorophosphate (H3OPF6) and hydrofluoric acid.

Additionally, such solutions often contain products derived from hydrolysis of the P-F bonds, including HPO2F2, H2PO2F, and H3PO4, and their conjugate bases.

Crystalline HPF6 has been obtained as the hexahydrate, wherein PF−6 is enclosed in truncated octahedral cages defined by the water and protons.

NMR spectroscopy indicates that solutions derived from this hexahydrate contain significant amounts of HF.

[5] Whereas a species with the formula HPF6 remains unknown, the analogous molecular hexafluoroarsenic acid (HAsF6) has been crystallized.