It can also be prepared by the oxidation of sodium bromate with xenon difluoride and water.
NaBrO3 + XeF2 + H2O -> NaBrO4 + 2HF + Xe
References
↑Georg Brauer (Hrsg.), with the collaboration of Marianne Baudler and others: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume I, Ferdinand Enke, Stuttgart 1975, ISBN3-432-02328-6, S. 333.