This paper shows the design of two control techniques, the linear quadratic Gaussian (LQG) control and the quantitative feedback theory (QFT) control for the dynamic model of a plate heat exchanger obtained from the principles of heat transfer in fluids. This model is linearized using Taylor series expansions for the three non-linear differential equations of the model. Both controllers are designed in MATLAB to control the temperature of the cold stream output of the heat exchanger, and their performance is compared by three types of analysis: the effect due to the uncertainty in the parameters, the response for a variable set-point, and the performance criteria based on the values of the error indexes.