The kinetics and mechanism of the curing process of a thermosetting blend formed by tetraglycidyl-4-4＇-diaminodiphenyl methane and N,N＇-bismaleimido-4-4＇diphenyl methane (BMI) cured in the presence of 4,4＇-diaminodiphenyl sulfone, was investigated in detail by Fourier transform infrared spectroscopy. Information on the molecular structure of the network formed upon curing was derived. Dynamic-mechanical measurements on dry samples indicated an interpenetrated polymer network-like structure. Sorption measurements at 70 degrees C showed a reduction of the water uptake at equilibrium in the presence of substantial amounts of BMI in the system (43.5% body weight). Finally, the dynamic-mechanical analysis of wet samples demonstrated a reduction of the plasticizing efficiency of the absorbed water in the presence of BMI.