In this paper is studied the temperature regulation problem of a continuous stirred tank reactor with two consecutive : and oscillatory exothermic reactions in which the heat of the reactions is unknown. A strategy to estimate the reactions’ heat from measurements of reactor temperature is proposed. This strategy is coupled with a linearizing-like feedback regulatory control. Practical convergence of this control scheme is proved when the uncertainty observer satisfies the high gain assumption. The performance of the uncertainty observer and the closed loop behavior is illustrated by means of numerical simulations.