In order to apply genetic algorithm to kinetic calculation and degradation study of polymers, extruded polystyrene (XPS) and rigid polyurethane (PU) were selected to perform a series of thermogravimetry (TG) analysis with four heating rates (5, 10, 15, and 20 degrees C/min) in nitrogen. XPS showed one-step degradation. Three commonly used isoconversional methods and genetic algorithm were used to calculate the activation energy of XPS. Calculation results by genetic algorithm were very close to those by isoconversional methods. Furthermore, a three-step reaction modeling was created to describe the degradation of PU. Agreement between experimental data and predicted values justified the accuracy of genetic algorithm calculation. Mass evolutions of reactants, intermediates, and products were separated from total mass loss. Then Fourier transform infrared (FTIR) and thermogravimetry-mass spectrometry (TG-MS) were employed to verify the validation of calculation results, which showed that temperature region and variation tendency were in good accordance with calculation by genetic algorithm. (C) 2015 Elsevier B.V. All rights reserved.