The organosolv ethanol process was adapted for converting hybrid poplar (Populus nigra L. x P. maximowiczii) into organosolv lignin and saccharide-derived chemicals, such as levulinic acid (LA), hydroxymethylfurfural (HMF), and furfural. The effect of process conditions (temperature, ethanol concentration, sulfuric acid dosage, and reaction time) on product yields was investigated using an experimental matrix designed with response surface methodology (RSM) and small Hartley composite design. The conditions ranged over 173-207 degrees C, 15-66 min, 2.3-5.7% H2SO4 (SA) on oven-dry wood (w/w), and 33-67% ethanol concentration (v/v). Results indicated that temperature, sulfuric acid loading, and their interaction had a significant effect on the yields of lignin and saccharide-derived chemicals. Comparative investigation of the organosolv process and acid process indicated that ethanol not only enhanced the delignification and production of organosolv lignin, but also improved the conversion yields of pentoses to furfural and hexoses to HMF and LA.