The concept of process intensification is applied to a CSTR polymerization reactor, where bulk reactions take place via styrene-free radicals, connected to a semi-flooded horizontal condenser; the aim is to operate the system in a safe and efficient way. The model developed was able to reproduce the major dynamic characteristics, even with the presence of non-condensable gases. The existence of such gases prevents the reactor from ever reaching a steady state, increasing the condenser pressure and the reactor temperature and reducing the area of contact and the mass of liquid in the condenser. To circumvent this problem, the control strategy of this work proposes a regular purge of the condenser gases in order to avoid a collapse of the system. In this context, different control algorithms were also analysed and it was concluded that a fast and reliable control of the reactor is only possible when advanced controllers are used. © 2005 Elsevier Ltd. All rights reserved.