Abstract—This paper presents a systematic approach for the design of temperature controller using genetic algorithms (GAs) for thermal power plant subsystems and investigates the robustness of the designed control law. The proposed approach employs GA search for determination of the optimal PI controller parameters for a previously identified nonlinear de-superheater of a 4X 325 MW thermal power plant. Results indicate that the proposed algorithm significantly improves the performance of the thermal power plant sub-system.