Hydrothermal gasification of isolated hemicellulose from the white poplar (Populus alba L.) and white poplar sawdust were studied to evaluate the effects of temperature (in the range of 300-600 degrees C) and the catalyst on the yield of the products. Hydrothermal gasification of poplar sawdust represents a future alternative to the waste management of agricultural residues, and industry waste. Hydrothermal gasification of isolated hemicellulose was helpful to understand and analyze the catalytic gasification characteristics of natural biomass material with high hemicellulose composition. The results indicated that hemicellulose isolated from poplar produced more gaseous products than poplar sawdust. The hemicellulose isolated from poplar wood left lower amount of ingasified solid residue than the biomass studied. Also yields of xylose, which is commercially available as hemicellulosic fraction and was studied in our previous study, was compared with isolated hemicellulose and real biomass. Among them, isolated hemicellulose had the highest yield in gasification. (C) 2020 Elsevier B.V. All rights reserved.