The conversion of plant biomass provides a sustainable pathway towards the production of renewable fuels. Hemicellulose, a readily available form of biomass, can be catalytically converted to provide a range of fuel molecules, from furans and sugar alcohols to alkanes and aromatics. Using ionic liquids as solvent and Brønsted acid catalysts for biomass deconstruction, we investigated the kinetics of hemicellulose (xylan) hydrolysis and the subsequent dehydration/degradation reactions. These findings were compared to those found for similar reactions involving cellulose. In 1-ethyl-3-methylimidazolium chloride ([Emim][Cl]) at 80 °C, we report that hemicellulose can be hydrolyzed to xylose in 90% yield, with 5 wt % dehydration products and 4 wt % humins, when water is added stepwise. This chemical process presents a viable pathway for producing sugars capable of being chemically (via dehydration/hydrogenation) or biologically (via fermentation) upgraded to potential fuel molecules.