An engineering kinetic model is applied to EPDM devulcanization in an extrusion process. Parameters that were included in the model are crosslink density, devulcanizing agent concentration, time, shear rate, and temperature. The extruder is considered as a series of plug flow and stirred tank reactors. The residence time is calculated using solid flow or liquid flow model, depending on the degree of decrosslinking. The model can accurately predict the decrosslinking degree inside the temperature boundary defined by the applied experimental conditions. Outside this boundary, the effect of chemical degradation on the measured conversion becomes more significant. (c) 2006 Elsevier Ltd. All rights reserved.