Biomass has received special attention as a resource for renewable energy. In particular, woody biomass and agronomic such as corn stover, corn cob, sugarcane waste, wheat or rice straw and forestry residues are on the rise as potential materials that can be converted into fuel ethanol. This work evaluated oxalic acid pretreatment of corn cob to produce ethanol by simultaneous saccharification and fermentation (SSF). The pretreatment was optimized by application of 2³ full factorial design and response surface methodology. Samples pretreated by different combination of temperature, oxalic acid concentration and residence time were subjected to enzymatic hydrolysis, using preparations of Novozyme 50013 and Accellerase 1000. The enzymatic saccharification of the cellulose fraction to glucose was favored using pretreated corn cob under conditions that yielded optimal hemicellulose solubilization (72.27 g/kg _{dry matter} of oxalic acid, at 180℃ for 50 min). The cellulose saccharification rate was inversely related to the amount of residual hemicellulose in the pretreated corn cob. The highest total sugar concentration (34.5 g/L) obtained by enzymatic saccharification was attained at 55ûC, pH 5.5 (medium citrate buffer) after 96 h using 10 FPU/g _{dry matter} at 10% dry solids. The saccharification, which depends on the enzyme loading rate and reaction time, had different yields of glucose from the cellulose and xylose from residual hemicelluloses. We will present results on simultaneous saccharification and fermentation of oxalic acid pretreated corn cob to ethanol using xylose-and cellobiose-fermenting Pichia stipitis CBS 6054.