Sewage sludge acquired from Giheung Respia treatment facility was characterized and converted into gas, bio-oil and char by pyrolysis. The rate of conversion as a function of temperature was obtained from differential thermogravimetric analysis (DTG) for different heating rates. The activation energy calculated from data selected conversions shows that the activation energy decreased with increasing conversion up to 10%, steadily increased from 10 to 70%, and substantially increased from 70 to 90%. Depending on the level of conversion, the values of activation energies varied between 181 and 659 kJ/mol. The gas product obtained in the experiment at 450 ℃, 20 min mainly included CO2 (30%), CO (23%) and CH4 (17%). The product yields of gas, oil and char were systematically studied by changing the pyrolysis temperature and residence time.