Ammonium hexafluorogallate is an inorganic chemical compound with the chemical formula (NH4)3GaF6.

[1][2] A mechanochemical reaction between ammonium fluoride and gallium fluoride trihydrate (GaF3·3H2O) at a ratio of 3:1 produces the compound.

[3] Also, a reaction of gallium(III) hydroxide, HF, and ammonium fluoride.

[4] Ammonium hexafluorogallate occurs in two polymorphic forms: tetragonal at low temperature and cubic at high temperature, with both transforming reversibly.

[6] It has colorless crystals, which are soluble in water.