AbstractThe absorption of Cl2 into aqueous bicarbonate and aqueous hydroxide solutions was studied both experimentally and theoretically. The rate coefficient of the reaction between Cl2 and OH− was estimated over the temperature range of 293–312 K and fitted by the Arrhenius equation: .If Cl2 were assumed to react only with water and OH− in an aqueous bicarbonate solution, the predicted absorption rate would be much lower than that experimentally measured. This suggests that Cl2 reacts with HCO3− in an aqueous bicarbonate solution. The rate coefficient of the reaction between Cl2 and HCO3− was estimated over the temperature range of 293–313 K and fitted by the Arrhenius equation: .More importantly, under absorption conditions, the amount of hydroxide consumed for absorbing a specific amount of Cl2 into an aqueous hydroxide solution is almost twice the amount of bicarbonate consumed for absorbing the same amount of Cl2 into an aqueous bicarbonate solution.