Fuel cells represent an important alternative energy source. This seminal work brings together world leaders in the field to provide a unique combination of state-of-the-art theory and computational and experimental methods, emphasizing molecular understanding of fuel cell catalysis. It covers fundamental principles and future challenges. It discusses research themes in the surface science approach to catalytic reactions at the solid-liquid and solid-membrane interface relevant to fuel cells. This is a core reference for electrochemists, electrocatalysis researchers, surface and physical chemists, chemical and automotive engineers, and researchers in academia, research institutes, and industry.