Mestrado em Engenharia Alimentar - Instituto Superior de Agronomia Sugar (and ethanol) production represent is one of the most important agro industries worldwide. Sugarcane straw is, along with sugarcane bagasse, one of the main waste products of these industries. Mainly, the straw has been more relevant with the passing years due to the changes in the harvest policy, with the replacement of manual harvest, in which the straw was burned, by mechanical harvest. It is therefore necessary to find processes that can contribute to the upgrade of this residue, which did not exist so far. In this work, we study and optimize one process for the upgrading of sugarcane straw, based on the use of autohydrolisis for biomass fractionation. This process was optimized, enabling a selective hydrolisis of hemicellulose, together with the production of xylo-oligosaccharides rich hydrolysate with high commercial potential to the food industry. In the optimal condition (210ºC (Log R0=3.85)), it was possible to obtain a xylo-oligosaccharide concentration of 11.12 g/L, corresponding to a 47.,49% yield, with low production of inhibitor compounds. Furthermore, it was possible to obtain solid residues with high cellulose and lignin content, whose enzymatic digestibility was increased, reaching a percentage of saccharification of 80%, relevant to their subsequent industrial use within biorefineries