This research investigates a remediation technique for antimony involving the adsorption and co-precipitation of aqueous antimony by in-situ formed ferric hydroxide. Flocculation is initiated by the oxidation of iron(II) with potassium ferrate(VI), K2FeO4, along with oxidation of the more toxic Sb(III) to Sb(V). A 3/1 mole ratio of Fe(II)/Fe(VI) and a total Fe/Sb mole ratio of 300/1 was needed to achieve total antimony concentrations below the maximum contaminant levels for drinking water (6 g/l).