This introduction to modern theories of enzyme catalysis presents the latest methods used to study quantum tunnelling in biological systems. Written in an accessible style, it is suitable for a wide audience but will be particularly useful to advanced level undergraduates, postgraduates and early postdoctoral researchers. The book starts with an introduction by Nobel Laureate, Rudolph A. Marcus. The reader is then guided through computational, kinetic and structural analysis of tunnelling and the synergy in combining these methods (with a major focus on H-tunneling reactions in enzyme systems). Edited by two leading experts, and bringing together the foremost practitioners in the field, this up-to-date account of a rapidly developing field sits at the interface between biology, chemistry and physics.