Halogenated elastomer compositions

A crosslinkable composition comprising a mixture of a halogenated elastomer selected from chlorinated or brominated interpolymers of a C4 to C7 isoolefin and a para-alkylstyrene comonomer, a crosslinking agent and from 0.1 to 10.0 parts by weight, per 100 parts of the halogenated elastomer by weight, of an accelerator compounds containing one or more groups of the formula

• —S—SO2—OM
• attached to a hydrocarbon radical or to an organic bridging group wherein M is a monovalent metal, the equivalent of a multivalent metal, a monovalent ion derived by the addition of a proton to a nitrogenous base, or the equivalent of a multivalent ion derived by the addition of two or more protons to a nitrogenous base.