With the addition of sufficient hydroquinone to completely suppress the free radical polymerization, the kinetics of Michael addition polymerizations of N,N'-bismaleimide-4,4'-diphenylmethane (BMI) and barbituric acid (BTA) with BMI/BTA = 2/1 (mol/mol) in 1-methyl-2-pyrrolidone was investigated independently. A mechanistic model was developed to adequately predict the polymerization kinetics before a critical conversion (ca. 60%), at which point the diffusion-controlled polymer reactions started to predominate in the latter stage of polymerization. The Michael addition polymerization rate constants and activation energy in the temperature range 383423 K were determined accordingly. Beyond the critical conversion, a relatively stationary limiting conversion (ca. 69%) independent of the reaction temperature was achieved. A diffusion-controlled polymerization model taken from the literature satisfactorily predicted the limiting conversion data. POLYM. ENG. SCI., 2013. (c) 2012 Society of Plastics Engineers