An equation that can predict the interfacial tension between oil mixtures and water was developed: gamma = (gamma (1) -gamma (2)) exp(alphaV(0.7)) + gamma (2). Five oils were used in the development of this equation. Interfacial tension between mixtures of these oils and water was measured using a Kruss K12 tensiometer in the Wilhelmy plate mode. The model developed was able to predict interfacial tension values for different ratios of the oil mixtures/water systems investigated. The limitations of this model when applied to surface active components are also discussed.