Abstract Mono- and bismaleimides were evaluated as curing agents to determine the effect of structure on crosslinking ability. Activity of N-phenylmaleimide derivatives (monomaleimides) as crosslinking agents is highly dependent upon the substituent on the phenyl group. Activity of bismaleimides is likewise affected by the nature of the moiety connecting the maleimide rings. Isomaleimides and itaconimides are less effective curatives. Initiators for maleimide cures include peroxides and sulfur accelerators of the thiazole type. Saturated and unsaturated hydrocarbon rubbers, except those containing a high percentage of isobutylene units, are vulcanized by a maleimide-initiator system. One of the attractive features of a maleimide curing system is that physical properties of the cured rubbers are independent of curing temperature. Further, these vulcanizates have the good aging characteristics typical of nonsulfur-cured vulcanizates. In contrast to sulfur vulcanization, the maleimide curing systems do not markedly affect the ability of elastomers to crystallize when stretched. Therefore, the T50 test cannot be used to assess the state of cure of maleimide-natural rubber vulcanizates. Maleimides containing an appropriate second functional group can be used as self-accelerating curing agents or as adhesives.