The polycondensation (Michael addition) of a bismaleimide (BMI, N,N-4,4’-[(1-methylethylidene) bis (phenyleneoxyphenylene)] bismaleimide) with an aromatic diamine (DA, 4,4’-[1,3 phenylene bis (1-methylethylidene)] bisaniline), in a 1:1 molar ratio, was followed using SEC and FTIR techniques. The polycondensation followed a 2nd-order kinetics with an activation energy, E = 51 kJ mol(-1). The mass fraction of dimer varied with conversion following the statistical prediction for an ideal A(2) + B-2 polycondensation. At 60% conversion, gelation was observed. This was ascribed to a small advance in the BMI homopolymerization. Thermal degradation took place at T > 200 degrees C. The first step was, possibly, a reversal in the Michael addition reaction as revealed by the decrease in the concentration of CH2 groups observed in FTIR spectra.