In this paper, using a suitable model for propane thermal cracking and based on a cost function, the optimal temperature profile is obtained. To achieve the optimal temperature trajectory, the furnace is divided into several zones and proportional-integral-derivative controllers are used to control the temperature of each zone. According to temperature measurements available, two cases are considered. In the first case, it is assumed that the furnace wall temperatures at different points are measured along with the reactor outlet gas temperature. In the second case, we assume that the reacting gas temperatures inside the reactor at different points are available. Simulation results indicate that for the first case the optimal temperature profile can be achieved if an accurate model is available. In the case of model mismatch, a method has been proposed which results in a near optimal profile. For the second case, two different strategies for set point tracking are proposed and their performances are compared through simulation. The controller performance for load rejection is also evaluated.