The nonisothermal degradation kinetics of the copolymer poly(O,O-diethyl-O-allylthiophosphate-co-acrylonitrile), which was synthesized with O,O-diethyl-O-allylthiophosphate and acrylonitrile, were studied by thermogravimetry/derivative thermogravimetry techniques. The kinetic parameters, including the activation energy and the pre-exponential factor of the copolymer degradation process, were calculated by the Kissinger and Flynn-Wall-Ozawa methods. The thermal degradation mechanism of the copolymer was also studied with the Satava-Sestak method. The results show that the activation energies were 1.38.17 kJ/mol with the Kissinger method and 141.63 kJ/mol with the Flynn-Wall-Ozawa method. The degradation of the copolymer followed a kinetic model of a phase boundary reaction and the kinetic equation could be expressed as G(alpha) = 1 - (1 - alpha)(4) [where G(alpha) is the integral function of conversion and alpha is the extent of conversion of the reactant decomposed at time t]. The reaction order was 4. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: 3705-3709, 2010