A safe, convenient preparation of the reagent sodium tetrakis[(3,5-trifluoromethyl)phenyl]borate (NaBArF(24)) has been devised by utilizing a magnesium-bromine exchange reaction in the absence of metallic magnesium. Purified material was then rigorously dried over P(2)O(5) (NaBArF(24) with < 500 ppm H(2)O by mass) or recrystallized as a hydrate (NaBArF(24).2.6 +/- 0.1H(2)O). Accurate analysis of the water content of these samples by (1)H NMR was accomplished by using dimethylzirconocene [Cp(2)Zr(CH(3))(2)].