The salt [NH4]2[PO2(O2)F]·2H2O has been synthesised from the reaction of [NH4][H2PO4] with 48% HF and 30% H2O2 at pH 10â 11, maintained by the addition of aqueous ammonia, at an ice-bath temperature. The compound has been characterised by chemical analysis, i.r., and laser-Raman spectroscopic studies. Some properties of the compound are also reported.