A new selective brominating system Br 2 /SO 2 Cl 2 /zeolite, has been discovered. Partially cation-exchanged Ca 2+ -Y zeolite efficiently catalyzes the selective para-bromination of neat chlorobenzene (CB) by Br 2 /SO 2 Cl 2 affording a CB conversion of ∼89% and a para-selectivity of ∼97%. During the bromination reaction, SO 2 Cl 2 oxidizes HBr, prevents its accumulation within the zeolite pores and yields a more active brominating species. The Ca 2+ -Y catalyst was found to be stable under the bromination conditions, and can easily be regenerated by calcination. The Br 2 /SO 2 Cl 2 /Ca 2+ -Y brominating system could be applicable to other activated aromatic compounds such as o-xylene, toluene and fluorobenzene.