The aim of this work is to analyse the nonlinear behaviour of a low-density polyethylene reactor-separator-recycle system. A simplified dynamic model is derived based on the detailed model presented in Häfele (2004). A numerical bifurcation and stability analysis is performed to predict the region of stableoperation. As a result multiple steady states and oscillatory behaviour were found. The implications of these findings for practical process operation are discussed. © 2005 Elsevier B.V. All rights reserved.