The mechanism of the desulphurizing action of alkali cyanides on thiuram and xanthogen disulphides has been determined. The reaction is shown to take place in two steps, the intermediate products formed in the first step have been identified as disubstituted thiocarbamyl thiocyanates. These thiocyanates belong to a hitherto unknown series of organic sulphur compounds.Two methods for the preparation of the new thiocarbamyl thiocyanates are described.The mechanism of the formation of monoxanthogens by the action of acid chlorides on xanthates is shown to be similar to the formation of monosulphides by the action of cyanides on disulphides.The following new compounds are described: mixed thioanhydride of ethyl carbonic and isopropyl xanthic acids, C2H6OC (O)S.CS.OC3H7liquid; methyl phenyl thiocarbamyl isopropylxanthyl sulphide, C6H5(CH3)N.CS.S.CS.OC3H7, m.p. 42 °C.; ethylphenyl thiocarbamyl isopropylxanthyl sulphide, C6H5(C2H5)N.-CS.S.CS.OC3H7, m.p.41 °C.; methylphenyl thiocarbamyl thiocyanate C6H5(CH3)-N.CS.SCN m.p. 113.5–114 °C.; ethylphenyl thiocarbamyl thiocyanate, C6H5(C2H5)N.CS.SCN, m.p. 75.5 °C.; methylp-tolyl thiocarbamyl thiocyanatep-CH3C6H4(CH3)N.CS.SCN, m.p. 116.5 °C.: methylp-tolyl thiocarbamyl chloride,p-CH3C6H4(CH3)N.CS.Cl, m.p. 53–54 °C.; ethylo-tolyl thiocarbamyl chloride,o-CH3C6H4(C2H5)N.CS.Cl, m.p. 69 °C.; α1methylphenyl α11phenyl dithiobiuret, C6H5(CH3).N.C.S.NH.CS.NHC6H5, m.p. 123 °C.