In this work, the optimal temperature control of a styrene solution polymerization reactor with two different control algorithms is considered. DMC and PID control methods are used to accomplish the optimal temperature control of the polystyrene reactor, Reactor optimal temperature profiles at different initiator initiation concentrations were obtained by applying maximum principle to the mathematical model of the free radical batch polymerization reactor to produce polystyrene with desired conversion and molecular weight in a minimum time. The results obtained from the experimental implementation of DMC and PID controller for the control of optimal temperature path of the polymerization reactor were compared.