Switchgrass was used as a lignocellulosic feedstock for second generation ethanol production, after pretreatment using sulfuric acid-catalyzed modified clean fractionation based on NREL's (National Renewable Energy Laboratory) original procedure. Optimization of temperature, catalyst concentration and solvent composition was performed using Response Surface Methodology, and 59.03 +/- 7.01% lignin recovery, 84.85 +/- 1.34% glucose, and 44.11 +/- 3.44% aqueous fraction xylose yields were obtained at 140.00 degrees C, 0.46% w/w catalyst concentration, 36.71% w/w ethyl acetate concentration, and 25.00% w/w ethanol concentration. The cellulose fraction did not inhibit the fermentation performance of Saccharomyces cerevisiae and resulted in an ethanol yield of 89.60 +/- 2.1%. (C) 2012 Elsevier Ltd. All rights reserved.