The recently proposed approach for representing and predicting surface tension of aqueous electrolyte solutions [Chem. Eng. Sci. 56 (2001) 2879] is extended to the prediction of interfacial tension between an organic solvent and aqueous multi-electrolyte solutions. The method of Meissner was adopted in all the calculations of activity coefficient of electrolytes. Model parameters were determined by correlating interfacial tensions reported in the literature for 11 single electrolytes, including 10 inorganic salts and one inorganic acid at isothermal conditions. The correlation yielded an overall average absolute percentage deviation (AAPD) of 0.42. Using these model parameters, the proposed approach was successfully applied to the prediction of interfacial tensions available in the literature for aqueous FeCl3-HCl, NiCl2-FeCb-HCl and NiCl2-COCl2-FeCl3-HCl solutions with an AAPD of 5.73.