The effect of solvent proton affinity on the kinetics of the Michael addition polymerizations of N,N '-bismaleimide-4,4 '-diphenylmethane (BMI) and barbituric acid (BTA) in different solvents [N-methyl-2-pyrrolidone (NMP), N,N '-dimethylacetamide (DMAC), and N,N '-dimethylformamide (DMF)] were investigated. This was achieved by the complete suppression of the competitive free radical polymerization via the addition of a sufficient amount of hydroquinone (HQ). A mechanistic model was developed to adequately predict the polymerization kinetics before a critical conversion, at which point the diffusion-controlled polymerization become the predominant factor during the latter stage of polymerization, was achieved. The activation energy (E-a) of the Michael addition polymerization of BMI with BTA in the presence of HQ in increasing order was: NMP < DMAC < DMF, which was correlated quite well with the solvent proton affinity (NMP > DMAC > DMF). By contrast, the frequency factor (A) in increasing order is: NMP < DMAC < DMF. As a result of the compensation effect between E-a and A, at constant temperature, the Michael addition rate constant decreased with increasing solvent proton affinity. POLYM. ENG. SCI., 54:559-568, 2014. (c) 2013 Society of Plastics Engineers