S,S-Dialkyl-S-phenacylsulfonium salts undergo facile reduction by silanes bearing Si-H groups in the presence of a noble metal catalyst. This redox couple can be employed as a convenient initiator system for the cationic polymerizations of epoxides, oxetanes and vinyl ethers. The polymerizations of these monomers can be carried out in a conventional manner with neat monomer or under solution conditions. In this communication we also report the novel use of a two-component redox system in which the silane is delivered as a vapor to a thin film monomer sample containing the sulfonium salt. Typically, the polymerizations are rapid and exothermic. The use of optical pyrometry (infrared thermography) as a convenient method with which to monitor and optimize the aforementioned cationic polymerizations is described. Studies of the effects of variations in the structures of the S,S-dialkyl-S-phenacylsulfonium salt, the silane and the type of noble metal catalyst on the polymerizations of typical vinyl and heterocyclic monomers were carried out.