A reduction in glycerol price has been observed in the last years, considering it is a byproduct of biodiesel production. This fact has motivated studies about alternative uses for this compound, as in pretreatment of lignocellulosic biomass to produce ethanol, another biofuel of interest. In this context, glycerol acid-pretreatment of sugar cane bagasse (SCB). was evaluated in terms of temperature (80-120 degrees C), solid loading (2.5-7.5%), glycerol (85-95%) and acid concentrations (0.5-3%), and reaction time (10-60 min), using a 2(5-1) factorial design. The cellulose digestibility was further optimized for the variables temperature (120-130 degrees C), acid/SCB mass ratio (5-15%), and time (20-60 min). The optimal conditions were obtained at 130 degrees C temperature, 15% acid/SCB mass ratio, and 57.5 min reaction time, yielding a 68.5% digestibility. Moreover, a considerable amount of ethanol, 0.38 g/g biomass (0.57 g/L.h of productivity), was achieved using Saccharomyces cerevisiae, which also shows the efficacy of this pretreatment.