The need to substitute fossil sources of energy by others renewable and non-pollutant stimulates researches on conversion of lignocellulosic biomass into fermentable sugars for production of bioethanol. The clean and rapid method of sub/supercritical hydrolysis has been proven technically feasible in face of acid and enzymatic hydrolysis, with the advantages of no need of pre-treatment, shorter reaction time, lower corrosivity, lower residue generation, no use of toxic solvents and lower formation of degradation products. However, further optimization of operation conditions (temperature, time, solvent: solid proportion) and economic evaluation of the process are still needed so that it can be scaled-up to industrial level. A semi-batch unit equipped with a 50 mL reaction vessel was used to perform subcritical water hydrolysis of cellulose at 214 °C, 235 °C and 258 °C for 40-60 min and under 20 MPa. The optimal condition was applied to hydrolysis of sugarcane bagasse. Total reducing sugars were determined using a colorimetric method. The reducing sugars recovery rate increased up to a maximum and then decreased for the three temperatures. The hydrolysis process finished earlier for higher temperatures; however, the reducing sugars recovery decreased with temperature increase, possibly due to degradation of glucose. Therefore, the less aggressive condition, of 214 °C, was selected for sugarcane bagasse hydrolysis.