[en] The radical anions, OH, and H adducts of some maleamates and maleimides have been characterised by the 'in situ' radiolysis - e.s.r. method. The maleimide radical anions could also be formed by electron transfer from (CH₃)₂COH and C0₂^-, whereas the maleamate radical anions could only be produced by electron transfer from the stronger reducing agent (CH₃)₂C0^-. Furthermore, the maleamate radical anions are thought to have cyclic structures with an amidic proton 'bonded' across to the carboxyl group since this proton did not dissociate or undergo fast exchange with the solvent even at pH 13.7. (author)