A non-linear viscoelastic constitutive model for polyurea by assuming a separable time and strain dependent material behaviour was proposed in this study. The strain dependent function was described by a nine-parameter Mooney-Rivlin model whereas the time function was assumed to follow a Prony series. A method based on the finite time-increment formulation was used to calculate the material parameters using a simple fitting routine. The effectiveness and accuracy of the model was validated using existing compression and tension data from the literature. The proposed model was found to be very efficient in capturing the behaviour of polyurea under both compressive and tensile loadings for a wide range of strain rates. (C) 2012 Elsevier Ltd. All rights reserved.