Triploid poplar (Populus tomentosa Carr.) was fractionated with mild organosolv process, and the effects of varying catalysts (formic acid, triethylamine and sodium hydroxide) and solvents (methanol, ethanol, n-propanol and n-butanol) on the substrate's physicochemical characteristics were examined. The data showed that neither the degree of polymerization (DP), nor the relative crystallinity was significantly influenced under the seven runs. In comparison, the addition of NaOH was more efficient on hemicelluloses dissolution, resulting in lower yields and higher glucose content of the cellulosic fractions than formic acid and triethylamine. Correspondingly, the final ethanol concentration was significantly increased from 1.83 g/L to 3.86-5.09g/L. Besides, a certain amount of xylose (704.4-962.8 mg/L) was released in the hydrolyzates during the simultaneous saccharification and fermentation (SSF), which could be further isolated to improve the multiple utilization of raw material. This research provided some useful data for the application of mild organosolv fractionation on the utilization of whole biomass, especially for the recovery of hemicellulosic components. (C) 2012 Elsevier Ltd. All rights reserved.