Graphene–electrolyte systems are commonly found in cutting-edge research on electrochemistry, biotechnology, nanoelectronics, energy storage, materials engineering, and chemical engineering. The electrons in graphene intimately interact with ions from an electrolyte at the graphene–electrolyte interface, where the electrical or chemical properties of both graphene and electrolyte could be affected. The electronic behavior therefore determines the performance of applications in both Faradaic and non-Faradaic processes, which require intensive studies. This book systematically integrates the electronic theory and experimental techniques for both graphene and electrolytes. The theoretical sections detail the classical and quantum description of electron transport in graphene and the modern models for charges in electrolytes. The experimental sections compile common techniques for graphene growth/characterization and electrochemistry. Based on this knowledge, the final chapter reviews a few applications of graphene–electrolyte systems in biosensing, neural recording, and enhanced electronic devices, in order to inspire future developments. This multidisciplinary book is ideal for a wide audience, including physicists, chemists, biologists, electrical engineers, materials engineers, and chemical engineers.