The evolutionary behavior of syngas composition during the pyrolysis and gasification of chicken manure was examined at different temperatures and O-2 concentrations. A gas chromatography was used to quantify the syngas evolved. Pure nitrogen was used for pyrolysis while two different oxygen concentrations (21% and 10%) in nitrogen were used for gasification. Five specific temperatures examined during pyrolysis and gasification were from 600 to 1000 degrees C in steps of 100 degrees C. Higher O-2 concentration (21%) produced higher energy yields compared to lower O-2 concentrations. Initial 8-10 min yield produced CO2 dominant syngas from decarboxylation after which the compositions changed to equilibrium. High temperature and low O-2 concentrations yielded higher CO flow rates and amounts. Equilibrium H-2 content was reduced with an increase in O-2 concentration due to the rapid oxidation of H-2 in the presence of oxidative environment. CH4 was obtained from thermal cracking with its evolution being similar to that of other higher hydrocarbons evolved, albeit in smaller concentration. (C) 2016 Elsevier Ltd. All rights reserved.