Nowadays, there is a great interest in using lignocellulosic materials as substrate for the production of biorefi nery products. Eucalypti are good options to use as crops to obtain different kinds of biofuels and derivatives, since their plantations show high adaptation potential to soil and weather conditions in Uruguay. The basic process steps involved in the obtainment of biorefi nery materials are: pretreatment, hydrolysis, fermentation and products separation. As delignifi cation is an important process to obtain biorefi nery products, in this context the evaluation of the biological (BT) and hydrothermal (TT) pretreatment of different species of Eucaliptus was studied. The possibility of obtaining sugars, alcohols and organic acids was the main focus. The results of these investigations show a good production of reducing sugars (4-5 mg/mL for both BT and TT pretreatments), acetic acid (3-8 mg/mL for BT and 3-7 mg/mL for TT) and isopropanol (18-48 mg/mL for BT and 20-30 mg/mL for TT). In conclusion, the results show similar behaviours for BT and TT pretreatments, which is a quite important result since BT is cheaper and cleaner and thus a more attractive technology.