In this paper, we report the application of two different parameter adaptation schemes used to improve the performance of input-output linearizing control of an exothermic continuous stirred tank reactor (CSTR). The first technique is based on ensuring the stability of the control system in the sense of Lyapunov when there are variations in the parameters appearing linearly in the linearizing control law. The second approach considers recursive least squares for parameter estimation independent of the control system stability. When the reactor is subjected to conditions of extreme parametric sensitivity and unstable operating conditions in the presence of variations in the process parameters, the parameter adaptive approach to linearizing control exhibits satisfactory behavior in terms of offset free regulation and improved performance.