This work studied the reaction pathways involved in the depolymerization of cellulose and hemicellulose during the fractionation of lignocellulosic biomass using an isopropyl alcohol/water mixture as a solvent with the Raney-Ni catalyst. Model molecules such as cellulose and hemicellulose derived-products (glucose, sorbitol, erythrose, xylose, xylitol, glycerol) were used to understand the role of the catalyst on the depolymerization of these lignocellulosic fractions. The fractionation of sugar cane bagasse with the Raney-Ni catalyst was performed, a correlation between the different products formed, and the possible reaction pathways were proposed. The results obtained in this work show that the appropriate balance between hydrogenation and hydrogenolysis capacity might tune the selectivity to the desired product. It is important to notice that Raney-Ni is an unsupported catalyst. The support may add acidity, basicity, or redox properties that may play an important role in the determination of product distribution.