In the present work the phase diagrams of seven fatty acid binary mixtures were obtained by differential scanning calorimetry (DSC). These mixtures were formed by capric acid (C-10:0) with lauric acid (C-12:0), myristic acid (C-14:0), palmitic acid (C-16:0), or stearic acid (C-18:0) and by lauric acid (C-12:0) with myristic acid (C-14:0), palmitic acid (C-16:0), or stearic acid (C-18:0). The spline technique was used to compare the results of this work with prior results available in the literature for some of the investigated systems. The occurrence of the eutectic point in all systems and of the peritectic point in some of the systems was observed. The occurrence of the peritectic point can be associated with the difference in the number of carbon atoms of the fatty acid chains used in the mixture. The approach suggested by Slaughter and Doherty (Chem. Eng. Sci. < BO > 1995 , 50, 1679-1694) was used to model the solid phase, and the liquid phase was modeled using the Margules-2-suffix, Margules-3-suffix, UNIFAC Dortmund, and NRTL models. The best modeling results were obtained using the Margules-3-suffix with an average deviation between experimental and calculated values of 0.14%.