The pyrolysis of mustard straw and stalk was investigated at different heating rates from the ambient temperature to a temperature of 700 degrees C in a dynamic nitrogen flow of 40 cc/min. The thermogravimetric (TG) and derivative thermogravimetric analysis (DTG) profiles were examined for the entire degradation zone to determine the order of reaction, pre-exponential factor and activation energy. The orders of reaction were in the range of 0.61-1.02, activation energy in the range of 10.83-21.63 kJ/mol and pre-exponential factor was in the range of 15.67-27.2 min(-1). This study of kinetics of pyrolysis of this abundant biomass is helpful in developing the mechanism of a thermochemical conversion process. (c) 2006 Elsevier Ltd. All rights reserved.