A model for the steady-state operation of styrene polymerization in a tubular reactor considering radial variation of the relevant variables was solved by the method of lines using either finite volume discretization or global spline orthogonal collocation. The finite volume solution has shown to be slightly more efficient and more robust than the orthogonal collocation solution. The former solution was used to optimize the steady-state operation of a three-section tubular reactor by selecting the wall temperature of each section. The optimization target is to obtain maximal conversion with minimum polymer polydispersity. These conflicting objectives were joined in a parametric global objective function. As it is multimodal, its global minimum for each value of the parameter was obtained by the particle swarm optimization method. The optimal operational conditions allow the production of polymers with lower polydispersity at the same conversion level obtained when uniform temperature exists at the reactor wall. (C) 2003 Elsevier Science Ltd. All rights reserved.