A process for producing a halogenated isoolefin copolymer involves contacting an unsaturated isoolefin copolymer cement, the cement comprising an unsaturated isoolefin copolymer dissolved in an organic solvent, under halogenation conditions with a halogenating agent and an aqueous solution of a potassium salt-based oxidant to form a two-phase reaction medium comprising an organic phase and an aqueous phase, the oxidant capable of converting hydrogen halide to free halogen. The process provides improved halogen recovery, is less sensitive to the presence of water, and makes use of more stable and less environmentally damaging oxidants.

A process for producing a halogenated isoolefin copolymer involves contacting an unsaturated isoolefin copolymer cement, the cement comprising an unsaturated isoolefin copolymer dissolved in an organic solvent, under halogenation conditions with a halogenating agent and an aqueous solution of a potassium salt-based oxidant to form a two-phase reaction medium comprising an organic phase and an aqueous phase, the oxidant capable of converting hydrogen halide to free halogen. The process provides improved halogen recovery, is less sensitive to the presence of water, and makes use of more stable and less environmentally damaging oxidants.