Mechanisms and kinetics of non-isothermal polymerization of N,N'-bismaleimide-4,4'-diphenylmethane (BMI) with barbituric acid (BTA) in dimethyl sulfoxide (DMSO) were investigated. The polymerization of BMI with BTA in DMSO was characterized by using differential scanning calorimeter (DSC), electron spin resonance (ESR) and H-1-NMR techniques. The polymerization was primarily governed by the Michael addition reaction and azaMichael addition reaction mechanisms. By contrast, free radical polymerization mechanism of BMI/BTA could be ruled out in DMSO medium. Model-free (isoconversional) method in combination with model-fitting method were used to determine triplet kinetic parameters for the polymerization of BMI with ETA in DMSO. Average activation energy (E-alpha) and pre-exponential factor (A(alpha)) were ca. 51 kJ mol(-1) and 1.33 x 10(6) min(-1) in the fractional conversion (alpha) range 0.1-0.9, respectively. The polymerization of BMI with BTA was primarily reaction-controlled [f(alpha) = (1 - alpha)].