Ethyl ethane thiosulphonate (I) and diethyl disulphide(Ⅱ)give well-defined waves with E_1/2 of-0.65 V and-1.35 V (vs.S.C.E.) respectively in 1:1:1 (v/v) mixture of n-propanol, 0.25 M Na₂HPO₄ and 0.25M KH₂PO₄ at pH 6.5, which was found to be the most satisfactory solvent and supporting electrolyte in our work.The wave-heightconcentration relations of I in the range of 0.57-6.4 mM and Ⅱ of 1.6-11 mM are linear.Both compounds can be determined simultaneously with an error less than ±10 per cent.