The solubilization of water by the single ionic amphiphile bis(2-ethyhexyl)phosphoric acid (D2EHPA) and the single nonionic surfactant Span 80 in a nonpolar medium has been investigated. The hydrodynamic, optical, and other various analytical techniques were extensively employed to study the physicochemical nature of the microstructures formed in D2EHPA/n-dodecane/water and Span 80/n-dodecane/water solutions. An analytical model based on geometrical assumptions of the spherical shape of the reversed micelles has been developed. The proposed model correlates, among several others, the aggregation number, and, thus, the size of microstructures with parameters such as the hydrocarbon chain length of the surfactant molecule, its concentration and volume fraction occupied by the reversed micelles, etc., the latter is being estimated from the Einstein viscosity equation and its two modified versions reported by Guth and Simha and Vand. Assuming the spherical shape of the aggregates, the Einstein equation was found to fit the experimental data of the D2EHPA solutions very well; however, Vand＇s equation was found to be more suitable to fit those of Span 80 solutions. The molecular associates formed by D2EHPA were mostly dimers; however, relatively larger microstructures were formed by Span 80, the higher the concentration the smaller the size with a tendency to leveling off and the shape is nonspherical. The basic structural parameters, that is, the aggregation number, reversed micelle, and water pool radii were derived, and a good agreement between the experimental and the predicted data from the model was found.