The selective acid hydrolysis of lignocellulosic material to produce the most utilized rare sugars that can be derived directly from biomass, such as xylose, mannose, galactose, arabinose, and rhamnose is examined. The most important utilization of sugars is related to production of biofuels, such as ethanol and hydrogen through fermentation. The most important commercially utilized rare sugars are xylose, mannose, galactose, arabinose, and rhamnose, which all can be prepared via acid hydrolysis of biomass. L-Xylose can be hydrogenated or enzymatically transformed to xylitol, which is a sweetening agent and is also used for preventing tooth decay, and acute otitis. Galactitol, the sugar alcohol of galactose, is prepared by catalytic hydrogenation of galactose. It can be used as a carrier for therapeutic agents. L-Arabinose can be chemically epimerized to L-ribose in the presence of molybdenum compounds or by using xylose isomerase as a catalyst.