The ethanol-based pulping of Eucalyptus globulus by the ALCELL(R) process was studied to determine the optimum cooking conditions. In the first set of experiments the influence of chip size, chip impregnation, liquor-to-wood ratio and cooking additives was studied. Once the more convenient values for these variables were established according to kappa number, yield and viscosity, a surface response method was used to determine the influence of cooking temperature, cooking time and ethanol concentration on autocatalyzed pulping process. The developed models indicate that a high screened pulp yield (56%) and acceptable kappa number (23) and viscosity (1030 mL/g) can be obtained when cooking conditions are around 185 degrees C, 110 min and 50% of ethanol.