This study presents a semi-empirical kinetic model for the prediction of monomer conversion and average molecular weight during pseudo-living radical polymerization of methyl methacrylate with tetraphenyl biphosphine as the initiator in bulk, using UV light as the energy source. The model incorporates the chain-transfer to the initiator. which has been shown to be an important reaction for controlling the molecular weight of formed polymers. To solve the set of proposed kinetic equations the method of statistical moments was employed. The kinetic parameters estimated by fitting the initiator conversion data and monomer conversion data were used for modeling the molecular weight profiles, which were in a fair agreement with the experimentally measured average molecular weights. The pseudo-living radical polymerization scheme is characterized by having reversible termination steps. The proposed circular reaction mechanism was lumped in the empirical power-law reaction rate expression, which seemed to be successfully employed in the model development. The modeling results may be used for the characterization of the polymerization process studied as well as for the prediction of the polymerization behavior at monomer conversions up to 30%. (C) 2001 Elsevier Science Ltd. All rights reserved.