This book is a brief introductory text of the fundamental electrochemistry that is essential for important biomedical areas including electrophysiology, biosensors and even gene technology. The book targets readers who generally lack a substantial background knowledge in physical chemistry or the basic concepts in electricity for understanding most of the electrochemical textbooks, monographs or research articles. The contents are expressed in a concise and concept-by-concept manner with basic material such as math or optional applications appended in the appendices. Hopefully, it will be a quick and efficient solution for those who are eager to understand, handle and even develop an electrochemical method or tool by themselves. Co-publish with National Taiwan University. Distributed worldwide by World Scientific Publishing Co. except Taiwan. Readership: Students, professionals, biomedical researchers and general public.