A one-step electrochemical synthesis of 1,3-dinitro compounds from aromatic and heteroaromatic aldehydes and nitromethane has been developed. in the procedure. an electrogenerated base is prepared by cathodic reduction of air-saturated nitromethane solutions. Then the aldehyde is added and allowed to react. The reaction presumably proceeds in thrice base-catalyzed steps: addition of nitromethane to the aldehyde to form a nitroalcohol, dehydration of the nitroalcohol to produce nitroolefin. and Michael addition of nitromethane to the nitroolefin. The synthesis produces the 1.3-dinitro products in very good yields when the aryl group is electron-donating in character. For less strongly electron-donating groups, only moderate yields are obtained and with electron-withdrawing groups the reaction tends to stop at the stags of the nitroalcohol. For purposes of comparison, four of the products were prepared in a multistep synthesis with the last step being the cathodically promoted Michael addition of nitromethane to the nitroolefin. It was found that this last procedure was also successful in forming the 1,3-dinitro derivative from 2-thiophenecarbox-aldehyde and nitroethane in good yield and ail three isomers of the product were separated and characterized. The stereochemical identity of one isomer was proved by X-ray crystallography whereas that of the other two was established by comparison of. nuclear magnetic resonance spectra with those of the isomers of an analogous compound of known stereochemistry.