Book excerpt: This unique book is at the nexus of modern software programming practices and electrochemical process engineering. It is the authoritative text on developing open source software for many applications, including: • fuel cells; • electrolyzers; and • batteries. Written by experts in the field in the open source computational fluid dynamics (CFD) code suite OpenFOAM, this book is intended for process engineering professionals developing practical electrochemical designs for industry, as well as researchers focused on finding tomorrow’s answers today. The book covers everything from micro-scale to cell-scale to stack-scale models, with numerous illustrations and programming examples. Starting from a clear explanation of electrochemical processes and simple illustrative examples, the book progresses in complexity through a range of diverse applications. After reading this book, the reader is able to take command and control of model development as an expert. The book is aimed at all engineers and scientists with basic knowledge of calculus and programming in C++.