In the last years, bioethanol production from lignocellulosic materials is receiving more attention from researchers since it is an abundant raw material in certain regions, it is cheaper, does not compete with foods like sugarcane or corn, and can reduce up to 86% of carbon dioxide emissions when compared with gasoline. However, the process economy is linked to the pretreatment needed to make the cellulose accessible for further steps of enzymatic hydrolysis and fermentation. Then, the motivation of this work is to propose a MILP model to perform an optimal synthesis of the pretreatment for obtaining fermentable sugars from the Eucalyptus globulus specie. For this purpose, a General Disjunctive Program (GDP) is formulated. The obtained results suggest that there is a small difference between a two-step pretreatment process (pretreatment with posthydrolysis) and one-step pretreatment of diluted acid process. (C) 2016 Elsevier Ltd. All rights reserved.