A series of iodonium tetrakis(pentafluorophenyl)gallate photoinitiators were employed to catalyze the photopolymerization of three typical epoxy resins. Rates of photoacid release were compared using Quinaldine Red as acid indicator in either acetonitrile or ethanol. A new fluorescence probe technique was successfully employed to follow the cross-linking kinetics of the epoxysilicone oligomer in real time. The results show that these new salts are the most soluble, most reactive photoinitiators with the desirable stability in monomer formulations in this family.