Bifunctional allyl tetrahydrothiophenium hexafluoroantimonate was synthesized via a one-pot reaction of 3-chloro-2-chloromethylpropene with thiophene in the presence of sodium hexafluoroantimonate. The initiation capability of this salt, in conjunction with a photochemical free radical source such as 2,2-dimethoxy-2-phenyl acetophenone and benzophenone, via an addition-fragmentation mechanism in the cationic polymerization of cyclohexene oxide and butyl vinyl ether is investigated.