The use of two dibenzo[a,c]phenazine derivatives, 10,13-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)dibenzo[a,c]phenazine and 10,13-bis(4-hexylthiophen-2-yl)dibenzo[a,c]phenazine are reported as photosensitizers for diaryliodonium salt photoinitiators. Novel dyes based on the dibenzo[a,c]phenazine skeleton are shown to be efficient in carrying out the cationic photopolymerizations. Representative examples of different types of monomers including epoxide, and vinyl monomers are polymerized in the presence of the photosensitizers and diphenyliodonium hexafluorophosphate (Ph2I+PF6-). Polymerizations are initiated at room temperature using long wavelength UV and visible light, and monitored by optical pyrometry. The photopolymerization of an epoxide monomer via solar irradiation is also demonstrated. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 32993303, 2011