The electrolytic reductive dechlorination of 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT) in the ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF(4)]) in the presence of a cobalamin derivative afforded 1,1'-(ethylidene)bis(4-chlorobenzene)(DDO) and 1,1'-(ethenylidene)bis(4-chlorobenzene)(DDNU) with 1,1'-(2-chloroethylidene)bis(4-chlorobenzene)(DDMS); the enhanced reactivity, as well as the recyclability of the cobalamin derivative catalyst in IL, makes the present system more efficient for the development of "green" technologies.