In this study, the efficient conversion of Helianthus tuberosus L. (Jerusalem artichoke) to sugar, 5-hydroxymethylfurfural (5-HMF), and levulinic acid (LA) were investigated using a Bronsted acid-catalyzed hydrothermal reaction. From this approach, the optimal amounts and reaction conditions for total reducing sugar (TRS), 5-HMF, and LA were as follows: 444 g kg(-1) of TRS yield (150.4 degrees C, 14.6 kg m(-3) sulfuric acid, and 9.8 min), 193 g kg(-1) of 5-HMF yield (166.0 degrees C, 4.6 kg m(-3), 30.8 min), and 323 g kg(-1) of LA yield (185 degrees C, 30.8 kg m(-3), 33.7 min). In terms of combined severity, the TRS and 5-HMF concentrations decreased linearly with increasing combined severity, whereas, the LA concentration was increased at a high combined severity factor. The H. tuberosus L. may be useful as a significant feedstock for the production of platform chemicals such as 5-HMF and LA. (C) 2015 Elsevier Ltd. All rights reserved.