Decomposition kinetics of primary sewage sludge (PSS) and synthetic faeces (SF), of various moisture contents, were investigated over different reaction times and temperatures using a hydrothermal batch reactor. Solid decomposition of PSS and SF was first-order with activation energies of 70 and 78 kJ/mol, and pre-exponential factors of 4.0 x 10(6) and 1.5 x 10(7) min(-1), respectively. Solid decomposition was significantly affected by reaction temperature more so than reaction time. Higher temperature resulted in higher solids conversion to hydrochar. Equilibrium solid hydrochar yields (relative to the original dry mass used) were 74%, 66%, 61% and 60% for PSS at 140, 170, 190 and 200 degrees C respectively, and 85%, 49%, 48% and 47% for SF at 140, 160, 180 and 200 degrees C respectively. Energy contents of the hydrochars from PSS carbonised at 140-200 degrees C for 4 h ranged from 21.5 to 23.1 MJ/kg, and increased following carbonisation. Moisture content was found to affect the Hydrothermal Carbonisation (HTC) process; feedstocks with higher initial moisture content resulted in lower hydrochar yield and the extent of carbonisation was more evident in feedstock with lower moisture content. The results of this study provide information useful for the design and optimisation of HTC systems for waste treatment. (C) 2013 Elsevier Ltd. All rights reserved.