As the subtitle indicates, the overriding intention of the authors has been to provide a practical guide to the design of electrolytic plant. We wanted to show that the procedures for the design and optimization of such a plant are essentially simple and can be performed by readers comparatively new to the electrochemical field. It was important to realize that electrochemical engineering should not be confused with applied electrochemistry but had to be based on the principles of chemical engineering. For this reason, reference is often made to standard chemical engineering texts. Since this is a practical guide rather than a textbook, we have included a large number of worked examples on the principle that a good worked example is worth many paragraphs of text. In some examples we have quoted costs, e.g., of chemicals, plant or services.