This paper describes the application of Nonlinear Generalised Minimum Variance control (NGMV) to a tubular flow reactor. The Armfield tubular flow reactor was used to investigate the behaviour of such reactors, on a scale smell enough to allow case of operation but capable of demonstrating Large scale reactor effects. A cooling coil as well as a thermostat was fitted for temperature versatility. Conventional PID was applied by using on-line vision basic and Window＇s 95 for temperature control. The materials of construction are suitable for most reactants, The second order reaction was selected between ethyl acetate and caustic soda. The coefficient of the reaction was calculated by well-known bimolecular reaction equation. The reactor is simulated using the material balance on caustic soda. The model equations are solved by means of the coupled central finite difference and Runge-Kutta-Fehlberg methods. The controlled variable is sodium hydroxide conversion. Imposed disturbances consist of load changes. Controlling variable is sodium hydroxide feed flow rate.The NGMV controller is based on NARMAX model. With the aim of modified input output models, the present work shows that the NARMAX model provides very good representation for nonlinear systems.