A helium-neon laser was used as a light source to induce the photopolymerization of ethoxylated trimethylolpropane triacrylate in aqueous solution. A nearinfrared spectrometer was used to follow the polymerization. Methylene blue (MB) and triethanolamine were used as the basic photoinitiation system, and novel accelerators to the two-component initiation system were investigated. The three-component photoinitiation systems containing cobaltic complexes as accelerators were found to be very efficient in initiating the polymerization of the aforementioned water-soluble monomer, and the efficiency was higher than that initiated by MB/triethanolamine/diphenyl iodonium chloride, which has been reported previously. Twin redox cycles between MB and cobaltic complexes was proposed to explain the acceleration effect of the cobaltic complexes. (C) 2004 Wiley Periodicals, Inc.