A method for characterizing and predicting the performance of demulsifiers that involves the relationship between the film pressure of the demulsifier and the normalized area and the solvent properties of the demulsifier has been developed. This procedure can be used both to choose the proper demulsifier and to develop effective new compounds by determining the effect of changes in the interfacial properties of different solvents. This article highlights some of the results on the basis of the study of demulsifiers (surfactants) efficacy in different solvents and discusses the surface active behavior of selected demulsifiers and identifies how Us efficacy can be enhanced by changing its bulk physiological behavior. The surfactant activity of the demulsifier is dependent upon the bulk phase behavior of the chemical when dispersed in the crude-oil emulsions. This behavior can be monitored by determining the demulsifier pressure-area isotherms for adsorption at the crude oil-water interface. The demulsifier concentrate is generally too viscous to be handled neatly, so a solvent is added to improve handling. However, careful selection of the solvent can significantly improve the surface activity of the demulsifier. It is proposed that the correct solvent is one that allows the demulsifier to dissolve totally without irreversible aggregation. The consequences of this solvent selection are improved surfce activity and emulsions resolution efficiency.