The bifluoride ion is an inorganic anion with the chemical formula [HF2]−.

The commercial production of fluorine involves electrolysis of bifluoride salts.

The bifluoride ion has a linear, centrosymmetric structure (D∞h symmetry), with an F−H bond length of 114 pm.

[4] Salts, such as potassium bifluoride and ammonium bifluoride are produced by treating fluoride salts with hydrofluoric acid: Potassium bifluoride binds a second equivalent of HF:[5] Heating these salts releases anhydrous HF.

In these processes, bifluoride breaks down silicon oxides, doing more effectively than HF (~4.5 times faster).