Chemical reaction engineering is at the core of chemical engineering education. Unfortunately, the subject can be intimidating to students, because it requires a heavy dose of mathematics. These mathematics, unless suitably explained in the context of the physical phenomenon, can confuse rather than enlighten students. Bearing this in mind, Reaction Engineering Principles is written primarily from a student’s perspective. It is the culmination of the author’s more than twenty years of experience teaching chemical reaction engineering. The textbook begins by covering the basic building blocks of the subject—stoichiometry, kinetics, and thermodynamics—ensuring students gain a good grasp of the essential concepts before venturing into the world of reactors. The design and performance evaluation of reactors are conveniently grouped into chapters based on an increasing degree of difficulty. Accordingly, isothermal reactors—batch and ideal flow types—are addressed first, followed by non-isothermal reactor operation, non-ideal flow in reactors, and some special reactor types. For better comprehension, detailed derivations are provided for all important mathematical equations. Narrative of the physical context in which the formulae work adds to the clarity of thought. The use of mathematical formulae is elaborated upon in the form of problem solving steps followed by worked examples. Effects of parameters, changing trends, and comparisons between different situations are presented graphically. Self-practice exercises are included at the end of each chapter.