A non‐adiabatic CSTR with an irreversible first order reaction is investigated. When the original non‐linear system is transformed into the linear system, two adjustable parameters are introduced into the linear system. The tuning of the controller is done by pole assignment techniques in the linear system. Suitable system parameters and appropriate controller gains are also obtained. By numerical simulations, the performance of the controller is favorably compared with the results obtained by Hoo and Kantor.