To produce a certain polymer with desired properties, some of polymerization variables should be controlled. In this paper, a oil bath was designed and constructed for the heating and cooling of the reactor. Then, a mechanistic model was developed for the solution polymerization of methyl methacrylate in a batch reactor. This model is highly non-linear. A Globally Linearizing Control (GLC) strategy was applied to control the reactor temperature. A linear PI controller was designed to eliminate the error. The controller performance was viable and the previously developed GLC method is suitable for the oil heating system.