Hydrothermal conversion (HC) can be used to convert sewage sludge into fuel-like products. The investigation of biomass compositions conversion can facilitate the understanding of reaction pathways. HC of dewatered sewage sludge (DSS) is conducted in sub-/supercritical water with batch reactors. Hemicellulose has the highest conversion efficiency of 99.1 wt %, followed by crude protein, cellulose, lignin, and lipid/oil. The total gas and H-2 yields increase slowly from 200 to 300 degrees C, then sharply rise up from 350 to 450 degrees C. At 450 degrees C, the H-2 yield reaches to the maximum of 0.70 mol/kg organic matter. HC of DSS includes reactants degradation to intermediates and final products formation from intermediates. The water-soluble products (WSPs) are formed throughout the HC process, the oil-phase products (OPs) are mostly produced at low temperatures (250-350 degrees C), and char and gases are mainly generated at higher temperatures (above 350 degrees C). (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.