The radical polymerization behavior of N-substituted citraconimides, 1, 1, 2-trisubstituted ethylenic monomers, was investigated. N-Alkylcitraconimides were found to homopolymerize in bulk at 60°C to give polymers with molecular weight of 680010000, except methyl and ethyl derivatives. Polymerization of N-phenylcitraconimides in benzene at 60°C or in bulk at 120°C gave polymers with relatively low molecular weight from 700 to 2000. From thermogravimetric analysis, the initial and maximum decomposition temperatures for poly(N-isopropyl-citraconimide) were 309 and 365°C, respectively, and these were lower than those for poly(N-isopropylmaleimide) by about 40°C.