Microalgae have been established as an excellent source of biomass for biodiesel production. However, the high free fatty acids content of the oil hinders the oil refining by conventional processes. The aim of this study was to separate neutral lipids in high acidity oils, such as microalgae, by determining the equilibrium data of the extraction system including triacylglycerol, free fatty acids, hexane, and hydrous ethanol (95%). Because the microalgae oil has a complex composition, a model oil blend analogous infatty acid composition to Desmodesmus communis oil was used. Experimental equilibrium curves (binodal) and tie-line composition were determined for oil blends with 2, 20, and 40% of FFA at 308.2, 313.2, and 318.2 K. Three empirical equations were used to correlate binodal data. The parameters of the equation with the best fit were used along with the phase separation data, which were obtained by gravimetric method, for the construction of the tie lines. The consistency of experimental tie-line data was checked by using the Othmer-Tobias and Bancroft equations. Neutral lipids distribution coefficient and FFA distribution coefficient, as well as the selectivity of hydrous ethanol, were calculated for all systems.