Due to the amount of compounds involved in the biodiesel production, liquid-liquid equilibrium data are essential in order to predict the proportions in which these compounds exist and subsequently proceed with a more efficient purification and aid in the design of the reactor and ponds. In this study, biodiesel was obtained through the basic transesterification of Brazil nut (Bertholletia excelsa) oil with methanol. Afterwards, the phase equilibrium behavior of this Brazil nut biodiesel + methanol + glycerol system was determined at T = 303.15 and 323.15 K and atmospheric pressure. The solubility curves were determined by the cloud-point method in isothermal conditions. The liquid-phases compositions were measured by determining their refractive index and densities. The Othmer-Tobias correlation was used to ascertain the quality of the experimental tie-lines. The results were correlated with the NRTL and UNIQUAC activity coefficient models. The calculated data showed good agreement with the experimental results, yielding a mean quadratic deviation in the composition of 1.49% and 1.18% using NRTL at 303.15 and 323.15 K, respectively, and 1.85% and 1.97% using UNIQUAC at 303.15 and 323.15 K, respectively Ver menos