Like many strong acids, hexafluorophosphoric acid is handled only in solution. It exothermically reacts with water to  produce oxonium hexafluorophosphate () and hydrofluoric acid.
Hexafluorophosphoric acid, like other strong acids, must be handled exclusively as a solution. It undergoes an endothermic reaction with water to form oxonium hexafluorophosphate () and hydrofluoric acid.