The photoinitiated radical polymerization of difunctional vinyl ether/maleate mixtures has been studied by real-time i.r. spectroscopy, a technique which records directly conversion vs time profiles for reactions occurring within seconds. Various factors were found to affect the polymerization kinetics, such as the photoinitiator concentration, the light intensity, the presence of oxygen and the composition of the monomer mixture. Whatever the monomer feed ratio, the two monomers were shown to polymerize at exactly the same rate, which reaches its maximum value for stoichiometric composition. The observed dependence of the polymerization rate on the monomer concentration argues in favour of a mechanism involving a donor-acceptor complex, with formation of an alternate copolymer.