The electrochemical synthesis of organic diseleno and ditelluro derivatives from an alkyl RX or aryl halide ArX, and elemental Se and Te, is carried out under controlled potential in a divided cell, or at constant current in an undivided cell filled with an aprotic solvent/supporting electrolyte system. The undivided cell is equipped with a Mg anode and contains a fluoride salt (Et₄NF.2H₂O) which gives the MgF₂ complex and avoids the formation of MgE₂ (E = Se, Te) during electrolysis. Elemental Se or Te is reduced as powder with sonication, or as a sacrificial cathode. Diorganyl dichalcogenides are thus prepared at room temperature by S_N2 substitution reactions in aliphatic series, and by S_NAr and S_RN1 substitution reactions in aromatic series. In the S_RN1 process, the key step, which is the coupling reaction Ar·/E₂^2-, is in competition with two main side-reactions, that is the hydrogenation of Ar· by the solvent and the cathodic reduction of Ar· to Ar^-. The highest yield of ArEEAr are obtained in MeCN and in the presence of a redox mediator. The technique involving the S_RN1 process is particularly suitable for aryl halides for which lithiation followed by Se or Te insertion cannot be carried out.