The course includes the description of three ideal reactor types: the batch reactor and the two continuous flow reactors involving plug or mixed type flow. The operation and optimum design of reactors for single and multiple reactions systems are examined. A section is dedicated to the study of temperature and pressure effects. The energy balance analysis is carried out for all reactor types. Non-isothermal problems involving adiabatic operation or operation with the use of heat exchangers are also examined. Cases of non-ideal flow reactors are described and the methodology for determining the residence time distribution using non-reactive tracers is presented. Finally, there is an introduction to the heterogeneous reactions between solid particulates and fluids. The shrinking core model is analyzed and characteristic examples of reactors are presented.