The objectives of this research were to produce a levulinic acid by two-step acid-catalyzed treatment of Quercus mongolica and to investigate the effect of treatment parameter ( reaction temperature range: 100-230 degrees C; sulfuric acid ( SA) concentration range: 0-2%) on the levulinic acid yield. After 1st step acid-catalyzed treatment, most of the hemicellulosic C5 sugars (15.6 g g/100 g biomass) were released into the liquid hydrolysate at the reaction temperature of 150 degrees C in 1% SA; the solid fraction, which contained 53.5% of the C6 sugars, was resistant to further loss of C6 sugars. Subsequently, 2nd step acid-catalyzed treatment of the solid fractions was performed under more severe conditions. Finally, 16.5 g/100 g biomass of levulinic acid was produced at the reaction temperature of 200 degrees C in 2% SA, corresponding to a higher conversion rate than during single-step treatment. (C) 2016 Elsevier Ltd. All rights reserved.