Ammonium hydrogen fluoride is the inorganic compound with the formula NH4HF2. It is produced from ammonia and hydrogen fluoride. This colourless salt is a glass-etchant and an intermediate in a once-contemplated route to hydrofluoric acid.

Potassium bifluoride is the inorganic compound with the formula KHF2. This colourless salt consists of the potassium cation and the bifluoride (HF2-) anion. The salt is used in etchant for glass.

Extremely hazardous in case of skin contact (corrosive, irritant), of eye contact (irritant), of inhalation.