Photopolymerization of 1,2-epoxy-6-(9-carbazolyl)-4-oxahexane (ECOH) initiated with diphenyl iodonium tetrafluoroborate and cyclopropyldiphenyl sulfonium tetrafluoroborate has been studied. The influence of diols on photopolymerization of ECOH has been examined. The results show that in the presence of 1,2-ethanediol (ED) reaction proceeds by the activated monomer mechanism. The monomer exponents were established for photopolymerization of ECOH in 1,2-dichloroethane with the iodonium salt and for that in the presence of ED.