The present work aims to study nominally known oleic systems – oleic acid, saponified oleic acid and biodiesel – in the presence of a biological surfactant, sodium cholate. For a better characterization of this system, dynamic light scattering and electrical impedance spectroscopy techniques were used. Through the first technique, it was possible to differentiate the systems by their sizes (hydrodynamic rays) and it was observed that the stereo effect caused by the interaction of different structures of the oleic material and the surfactant directly impacts the dimension of the formed particles. The Electrical Impedance experiment did not show differences in the electrical behavior of these particles, which shows that the electrostatic interaction between these particles does not vary significantly, regardless of the oleic material used.