The electrohydrodimerization reaction of dimethyl fumarate in the presence of cinnamonitrile and acrylonitrile was studied in dimethylformamide solution by rotating ring‐disk electrode, voltammetric and coulometric techniques. At potentials where only dimethyl fumarate is electroactive, the rate and mechanism of decay of the dimethyl fumarate anion radical are only slightly perturbed from the results obtained in the absence of cinnamonitrile and acrylonitrile. This is an indication that little or no cross‐coupling was occurring. At potentials where both dimethyl fumarate and cinnamonitrile are electroactive evidence for the occurrence of a solution oxidation‐reduction reaction consuming cinnamonitrile anion radical and dimethyl fumarate parent was obtained. In addition, the role of cis‐trans isomerization of radical anions in electrohydrodimerization reactions is discussed. Differences in the cyclic voltammograms of diethyl maleate in the presence of acrylonitrile when compared with those obtained in the absence of acrylonitrile and for dimethyl fumarate in the presence of acrylonitrile are observed.