The MTO process on SAPO-34 was modeled in a fundamental way using the single event concept combined with the Evans-Polanyi relationship. This approach together with a number of thermodynamic constraints leads to a drastic reduction of the number of independent parameters. These were determined from the experimental data using a combination of a hybrid genetic algorithm, sequential quadratic programming, and the Levenberg-Marquardt optimizer. The effect of the structure of reactant and product on the rate coefficients of the various types of elementary steps was illustrated. The effect of operating variables such as temperature and the methanol partial pressure was investigated using the kinetic model. The deactivation of the catalyst was modeled in terms of the amount Of C6+ olefins formed and trapped inside the SAPO-34 cavities. The effect of deactivation on the evolution with process time of the conversion and product yields of the MTO process was illustrated by the simulation of an isothermal fixed bed reactor.