A tetraalkylthiuram disulfide is prepared in a higher yield without formation of by-products by subjecting the corresponding alkali metal dialkyldithiocarbamate to electrolytic oxidation, which is carried out in a two-layer electrolytic solution consisting essentially of either (1) water and carbon disulfide or (2) water and a mixture of carbon disulfide and a halogenated alkane of higher density than water, the carbon disulfide being predominant in the mixture, by means of electrodes placed in the aqueous layer containing the dialkyldithiocarbamate. The resulting disulfide is extracted to the lower layer of the electrolytic solution and is recovered from the layer. The dialkyldithiodicarbamate can be continuously produced in situ by adding carbon disulfide and dialkylamine gradually to the aqueous layer of the electrolytic solution, which contains an alkalimetal hydroxide produced during the electrolytic oxidation of the dialkyldithiocarbamate.