AbstractAn X‐ray analysis was carried out of Na‐ Cs‐ and TIBF4 which proved to be isomorphous with the corresponding Perchlorates. The compound BF3. NaOH, isomorphous with NaBF4, should be formulated as the sodium salt of monohydroxyfluoboric acid; the hydroniumsalt of the same acid (BF3. 2H2O) formed the subject of a previous publication.From the dissociation pressure, the heat of dissociation of NaBF4and NaOH. BF3was determined. The relative stability of both compounds was disc