The objective of the present work is to evaluate the potential of water prehydrolysis of Eucalyptus wood hemicelluloses(mainly xylan) for bioethanol production.A primary water hydrolysis treatment of Eucalyptus wood was performed before the cooking stage to extract part of the hemicelluloses that otherwise would be dissolved in the kraft liquor and burned.The components of the hydrolysates extracted under different conditions were analyzed, which showed that xylose was main component of the hydrolysates and xylose concentration of H160B reached 16.56 g/L.The xylose-fermenting strains, Pachysolen tannophilus ATCC 32691, Candida lusitaniae CICC 1461 and yeast SHY07-1 were used to evaluate fermentability of the hydrolysates and the yeast SHY07-1 displayed excellent xylose-fermenting ability.A highest ethanol concentration of 5.75 g/L was obtained in hydrolysate H 160B at 48 h, corresponding to an ethanol conversion of 0.33 g/g with an ethanol productivity of 0.12 g/(L h) and a fermentation efficiency of 71.57%.