Homopolymerizations and copolymerizations of N-cyclododecylmaleimide (CDMI) were performed at 60 degrees C in the presence of azobisisobutyronitrile (AIBN) as an initiator in tetrahydrofuran. The initial rate of polymerization was R(p) = k[AIBN](0.50)[CDMI](3.4), where k is the rate constant. Overall activation energy (E) and frequency factor (A) were 19.2 kcal mol(-1) and 2.0 x 10(9) s(-1), respectively. The monomer reactivity ratios in the copolymerization of CDMI (M(1)) with styrene (ST; M(2)) or methyl methacrylate (MMA; M(2)) and Alfrey-Price Q, e values were determined as : r(1) = 0.10, r(2) = 0.102, Q(1) = 1.77, e(1) = 1.34 in CDMI-ST system; r(1) = 0.19, r(2) = 1.31, Q(1) = 0.91, e(1) = 1.58 in CDMI-MMA system. The thermostabilities of the polymers and copolymers were investigated by differential scanning calorimetry and thermogravimetric analysis.