Novel way rational and rigorous are to solve a complex process for low and high order differential equations by using a numerical techniques simulation of MATLAB software. A lot of solutions for different states problems depend on assumptions so as to be able to solve these problems. These assumptions are reduced the ability of solution and not give a real picture about the system. So, depends on numerical techniques by using MATLAB software in details to have a big understanding to all chemical reactions and design processes. In addition to the practical aspects, some of the more fundamental, often more abstract and topics are also discussed to permit the reader to understand the current literature. The book is organized into two main first part is studied in high details the kinetics of chemical reactions, design different reactors like plug flow, continuous stirred tank reactor, batch, fixed bed and fluidized bed reactors to let the reader to study the detailed kinetics to extend this to overall reactor behavior and second part is mixed between theoretical and solution by using MATLAB software in a very high details to use all tools inside this software for calculations.