It is shown that the liquid-liquid interfacial tension in binary and ternary aqueous-hydrocarbon systems at any temperature can be determined by knowing the molar compositions of the bulk fluid phases and a system-dependent constant. The system-dependent constant has been found to be related to Saturation adsorption. Based on these findings,a new equation has been proposed for reliable prediction of interfacial tension in aqueous-organic systems. The model is simple to use and reasonably describes the interfacial tension of binary water-hydrocarbon mixtures and some ternary aqueous-organic systems. The new equation shows an apparent inconsistency near the critical point which is explained using the underlying mono-molecular layer assumption. (C) 2009 Elsevier B.V. All rights reserved.