Thermogravimetric experiments of two different industrial sludge samples were carried out with nonisothermal temperature programs. The results indicated that the pyrolysis process contains three obvious stages and the main decomposition reaction occurred in the range of 200-600 degrees C. The distributed activation energy model (DAEM) was also proposed describing equally well the pyrolysis behavior of the samples. The calculated activation energy was ranged from 170 to 593 kJ/mol and 125 to 756 kJ/mol for S-LYG (sludge sample from chemical fiber factory) and S-QD (sludge sample from woody industry), respectively. The reliability of this model not only provided good fit for all experiments, but also allowed accurate extrapolations to relative higher heating rates. Besides, the FTIR measurement was also used to further understand the relationship between pyrolysis behavior and chemical structures for industrial sludge. (C) 2015 Elsevier Ltd. All rights reserved.