The photoinduced polymerization of a N-alkyl substituted bis-maleimide (MI) has been studied by real-time infrared spectroscopy. The polymerization of the neat monomer proceeds rapidly and extensively because of both its great absorbance in the UV-range, and the presence on the alkyl chain of easily abstractable hydrogen atoms, which are needed to produce the initiating radicals. Such photoinitiator-free resin was found to be less sensitive to oxygen inhibition than typical UV-curable acrylate resins, the peroxyl radicals formed being capable to propagate the chain reaction. This N-substituted bis-maleimide was also successfully used as monomeric photoinitiator to induce the crosslinking polymerization of acrylate monomers through the free radicals formed upon its photolysis. (C) 2004 Published by Elsevier Ltd.