AbstractPaper sludge and extraction liquor from water prehydrolysis of Eucalyptus chips before pulping are potential raw materials for ethanol production in an integrated forest biorefinery concept. Ethanol production from paper sludge, extraction liquor from water prehydrolysis of Eucalyptus chips, and a mixture of both using separate hydrolysis and fermentation were investigated. The hydrolysate composed of 51.01±0.72 g/L glucose, 30.11±0.09 g/L xylose, and 13.65±0.94 g/L cellobiose, which was obtained by enzymatic saccharification of the mixture at an initial consistency of 6% (w/v, expressed in terms of total carbohydrate mass), was used for ethanol production by yeast SHY07-1 without prior detoxification and nutrient supplementation. A final ethanol concentration of 36.82±0.35 g/L was achieved, corresponding to an ethanol yield of 0.45±0.04 g/g with a fermentation efficiency of 80.71±0.03% and an ethanol productivity of 0.31±0.01 g/(L h). This confirmed the feasibility of co-fermentation of these two materials for bioconversion to ethanol.