This paper addresses the optimization of batch polymerization systems, using a feasible path approach, with roots on Model Predictive Control (MPC) theory. The approach allows the reuse of many concepts previously developed for nonlinear MPC of continuous plants. It also provides an efficient and well-integrated methodology for the optimal supervision of discontinuous chemical processes. The application of this technique to the optimization of the batch suspension polymerization of vinyl chloride and the solution polymerization of methyl methacrylate is considered. Significant advantages associated to the use of this methodology are demonstrated with both examples, in terms of productivity gains and the capability of manufacturing products with pre-specified properties.