The reduction mechanism of vinclozoline, 3-(3,5-dichlorophenyl)-5-methyl 5-vinyl-1,3-oxazolidine-2,4-dione, iprodione, 3-(3,5-dichlorophenyl)-N-(1-methylethyl)-2,4-dioxo-1-imidazolidinecarboxamide, and procymidone, 3-(3,5-dichlorophenyl)-1,5-dimethyl-3-azabicyclo[3.1.0]hexane-2,4-dione, was studied in acetonitrile by electrochemical methods combined with GC/MS identification of products. Irreversible reduction was observed at about -2.2 V. The electron transfer reaction was coupled with subsequent chemical reactions yielding several final products. The main decomposition pathways included the elimination of the hetero-ring (producing chloroanilines and most likely diketones) and the cleavage of one or both chlorine atoms. Vinclozoline also yielded compounds that derive from the reductive elimination of the -O-C=O fragment (carbon dioxide) from the heterocyclic ring.