For the first time two-body interaction coefficients between any two molecules are considered to be non-identical. On this basis, various expressions involved in Flory theory have been deduced. and then utilized to compute surface tension of three ternary liquid mixtures. Prior to this, corresponding-states group-contributions method for the first time has been extended to three ternary liquid mixtures, viz. n-pentane + n-hexane + benzene, cyclohexane + n-heptane + toluene, 2,2,4-trimethyl pentane + cyclohexane + decane and some binary mixtures at 298.15 K. On comparing the computed values of surface tension by the present two approaches with experimental data, quite satisfactory results have been observed. (C) 2008 Elsevier B.V. All rights reserved.