Suspension polymerization reactions are commonly carried out in tank reactors designed with low values for the H/D ratio (Height/Diameter). As polymerization reactions are frequently high exothermic, the superficial area of these equipments are not enough high to adequately release the heat generated by the reaction. in this case, additional systems are necessary to provide cooling fluids with sufficiently low temperatures in order to maintain constant the polymerization temperature in the tank reactor. On the other hand, tubular reactors can be considered economically attractive because their high superficial area for heat exchange (high H/D) can improve temperature control and reduce operational costs. The present work uses a vertical tubular reactor to carry out the batch styrene suspension polymerization and evaluate the effects of the reactor and stirring system configuration on the polystyrene PSD (Particle Size Distribution). According to the results, besides a very good temperature control due to the reactor geometry, polystyrene particles with relatively narrow particle size distributions can be successfully produced in a stirred vertical tubular reactor.