Microemulsions have received widespread attention for industrial applications due to desirable low interfacial tension and high solubilization properties. These unique characteristics can only be achieved at the optimum condition where an equal balance between the surfactant-oil and surfactant-water interactions is obtained. The easiest way to attain the optimum condition is by a proper surfactant selection. Thus, several empirical approaches (i.e. hydrophilic-lipophilic balance (HLB), phase inversion temperature (PIT) or Winsor R-ratio etc.) have been proposed as convenient tools for characterize surfactants. Although, these existing methods provide an approximate estimation of the hydrophilic-lipophilic nature for most surfactants, they have some serious limitations. Recently, they have been proven inadequate for characterizing a newly developed class of surfactants known as extended surfactants. Therefore, the goal of this project is to develop an alternative indicator for characterizing extended surfactant. This new indicator is named as a surfactant characteristic parameter or a sigma parameter (R) of the hydrophilic-lipophilic difference (HLD). Preliminary results show a nice correlation between the sigma value and the hydrophilicity and lipophilicity of conventional surfactants. Furthermore, the sigma parameter method has also proven applicable for characterizing the hydrophilic-lipophilic nature of extended surfactants.