The conductance behaviour of certain potassium alkyl xanthates (alkyl : methyl, ethyl, iso-propyl, butyl and iso-amyl) was studied in 20, 40, 60, 80 and 100 mass% dimethylsulphoxide + water mixtures at 25 degrees C. The conductance data were analysed using the Fuoss (1978) conductance-concentration equation and the Fuoss computer program; values of the limiting molar conductance Lambda(0), association constant K-A and cosphere diameter R were derived. The limiting ionic mobilities of the individual ions are reported and an attempt is made to correlate the derived parameters obtained for the various systems in terms of the increasing sizes of the attached alkyl substituents in xanthate anions.