We report the first hydrothermal hydrolysis of curdlan, a water insoluble beta-1,3-glucan, to produce beta-1,3-glucooligosaccharides, which are high-value materials with health-benefiting activities. In this study, hydrothermal hydrolysis was tested for the liquefaction and saccharification of curdlan. The optimal hydrothermal hydrolysis conditions were 180 degrees C and 60min, respectively, resulting in a high degree of liquefaction (98.4%) and low by product formation. Under the optimal conditions, 17.47 g/L of beta-1,3-glucooligosaccharides was produced from 20 g/L of curdlan, representing a conversion yield of 87.4% (w/w). Using this process, beta-1,3-glucooligosaccharides were conveniently produced in a one-step reaction without any chemicals or enzymes. This hydrothermal hydrolysis for curdlan exhibited the best performance among various hydrolysis processes reported to date. This method can be applied to large-scale production of beta-1,3-glucooligosaccharides for the functional food and biopharmaceutical industries. (C) 2016 Elsevier Ltd. All rights reserved.