Phase behavior of microemulsions composed of Kolliphor HS 15, caprylic/capric triglycerides (GTCC), and water was investigated by phase diagrams and conductivity measurements. In addition, Delta G(CP)(0), Delta H-CP(0), and Delta S-CP(0) were also calculated because the clouding phenomenon is controlled by energy. On the basis of the preliminary: contribution to the variation of both Specific conductance and peak current, the monophasic phase could be divided into self-microemulsion and microemulsion regions. Besides, a shorter bicontinuous phase was formed as the composition closing to the boundary between two subregions. Furthermore, thermodynamic parameter showed that self-microemulson was more stable than that of microemulsion, which was further supported by cyclic voltammetry characterizing the two subregions. Dehydration of solvation layer as alpha(GTCC) increasing is responsible for the mechanism-of the liquid liquid phase separation process and therefore of the thermodynamic stability.