Elimination of the arsenic (III) impurity AsF 3 from anhydrous hydrogen fluoride has been demonstrated using a bench-scale apparatus (∼500mL of HF), with a Ag(II) salt AgFAsF 6 as a mediator. In this process, AsF 3 is oxidized by AgFAsF 6 to AsF 5 . In the next step, AsF 5 is eliminated from HF by reaction with NaF. The oxidizer, AgFAsF 6 , is reduced to AgAsF 6 which is regenerated to AgFAsF 6 by F 2 in HF at room temperature. This method can reduce the arsenic content in HF from a few hundred ppm to the industrially required level (<3ppm). The results for three other methods (distillation, oxidation by F 2 gas, and oxidation by K 2 NiF 6 ) are reported and compared with the AgFAsF 6 method in a preliminary examination (using ∼4mL of HF).