This first volume in the series discusses nonequilibrium thermodynamics and kinetics, particularly enzyme catalysis, for processes and systems in the steady state. Methods of mathematical modelling by means of network simulations are also treated, since they serve to assess the transient behaviour of a system on its way to a steady state. Water as a ubiquitous constituent plays an essential role in bioelectrochemical systems, hence its structure is carefully evaluated, both in the pure state and in the ionic hydration shell. Similarly, the interface between water and a membraneous or biocolloidal phase is of major importance. The phenomenon occurring at such interfaces, including diffuse double layers, as well as binding and adsorption of solutes, are examined.