AbstractA cubic equation has been derived that permits calculation of the composition of aqueous bromine solutions in terms of HOBr, BrO−, Br2, Br−3 and Br− as a continuous function of the pH, the initial oxidant concentration and the mole fraction of oxidant consumed. The calculations were performed by computer for the pH range 0–14 at bromine concentrations (c0) of 10−1 to 10−7 M. Throughout the course of an oxidation at pH 0 and c0= 10−4, bromine water is pure Br2. No Br−3 exists at c0 < 10−3. In the pH range 4–6, dilute bromine solutions are pure HOBr (+ equimolar Br−). For pH > 10, bromine water is pure BrO−, while at pH < 7, no BrO− is present. These conditions are unchanged during oxidant consumption.