Volume 1 of this Series is intended to give the reader a fundamental understanding of the key areas deemed essential to the study of bioelec­ trochemistry. A thorough grasp of the theory and methodology of these basic topics is vital to cope successfully with the complex phenomena that currently face investigators in most bioelectrochemical laboratories. Chapter 1 outlines the nonequilibrium thermodynamics and kinetics of the processes involved, stressing the connection between the two approaches. Particular emphasis is placed on the enzymes catalyzing cytosolic reactions and membrane transport. The techniques discussed are sufficient for the study of systems in the steady state, but systems that are evolving towards the steady state, or show some other time-depen­ dent behavior, require in addition the techniques of mathematical modelling. These are dealt with in some detail in Chapter 2, where network representation of the system is treated at length as the method of choice in carrying out appropriate simulations. In Chapter 3 attention is directed to the twin problems of water structure and ionic hydration.