2-Propenyloxy isoquinolinium hexafluoroantimonate and 2-methyl-2-propenyloxy isoquinolinium hexafluoroantimonate were synthesized and characterized. Their capability to act as initiator and co-initiator for the cationic polymerization of cyclohexene oxide (CHO) was examined. Both thermally and photochemically latent effectiveness of these salts in promoting polymerization of CHO at 70 degreesC and lambda = 350 nm, respectively was investigated. The accelearating effect of thermal and photochemical radical sources were also demonstrated. The contribution of electron transfer and addition-fragmentation mechanisms was discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.