Novel cationic initiators, p-substituted benzylanilinium SbF6- salts (1), were synthesized from the corresponding benzylchloride and N,N-dimethylaniline, where Cl- was exchanged with SbF6-. Their catalytic activities in the cationic polymerization of glycidyl phenyl ether (GPE) were examined and compared to that of benzylpyridinium SbF6- salts (2), latent thermal initiators previously reported by Endo et al. It was found that 1 acted as a latent thermal initiator in the cationic polymerization of glycidyl phenyl ether (GPE) above 80 degrees C for 10 min. Furthermore, 1 showed higher activity than 2 having the same p-substituents, except for a p-CI group in the cationic polymerization of GPE. Both the GPE polymer structure and the benzyl group reactivity in 1 or 2 indicate that 1 generates benzyl cations that are active species for the cationic polymerization of GPE, and that in cationic polymerization using 2, side reactions generating active species other than benzyl cations occur. [GRAPHICS]