This work presents the development of a kinetic model for simultaneous reactions of esterification and interesterification from macaw oil and methyl acetate using gamma-alumina as the heterogeneous catalyst. Experimental data varied between 225 degrees C and 300 degrees C, catalyst concentration of 2 wt%, 5 wt%, and 10 wt% and molar ratio (methyl acetate: Oil) of 10:1, 20:1 and 40:1. Arrhenius kinetic parameters were concomitantly estimated for all experimental conditions by minimizing the objective using a hybrid optimization algorithm. From the results, it could be verified that gamma-alumina is an active catalyst for both interesterification and esterification reactions with MeA and a high acid glyceride source. The simultaneous reaction system indicated an endothermic character at experimental conditions investigated. The FAME conversions presented a strong limitation of chemical equilibrium. Moreover, it could be verified that the esterification reaction produces about 80% of total fatty acid methyl esters and that acetic acid played the main role as a reagent through reactions with glycerine acetates and not as a catalyst. The proposed kinetic model satisfactorily fitted the experimental results. (C) 2020 Elsevier Ltd. All rights reserved.