This paper describes the design and analysis of a closed loop Fuzzy Logic Controller for temperature control system of a gas pilot plant. The overall model is built in MATLAB/Simulink- technical computing software that has adjustable structures where variables for the model and control strategies can be modified. Simulations have been performed for both controllers to observe the response. Results of the PI-Fuzzy Controller are compared with the response of the conventional PID controller. The PID controller response using Ziegler Nichols open loop, Ziegler Nichols closed loop and Cohen Coon method are presented and evaluated against the response of 3, 5, 7 and 9 membership functions of the PI-fuzzy Controller. © 2010 IEEE.