The present volume contains five chapters covering areas of contemporary interest in the fields of electrolyte solutions, the state of solvent molecules at electrode surfaces, charged colloid interfaces, surface chemistry of oxide electrodes and electro­ chemistry, and bioelectrochemistry of charge transfer complexes. The first chapter, by Barthel, Wachter, and Gores, covers the topic of conductance of nonaqueous pro tic and aprotic electro­ lyte solutions. This field is not only of intrinsic interest in itself, illustrating the important departures of ion-transport behavior in organic solvents from that, more well known, in water, but the information and extensive new data presented in this chapter will be of interest to those working with nonaqueous alkali-metal batteries where the conductivity and ion-association behavior of electrolytes in various solvents other than water is of great importance. The second chapter is devoted to a very fundamental and ubiquitous aspect of electrochemistry of electrodes: the state of solvent molecules, adsorbed and oriented, at their surfaces. The role of solvent adsorption and orientation in double-layer properties, it will be recalled, remained poorly understood until the early 1960s. This chapter, by Trasatti, gives a thorough account of the present state of knowledge of solvent orientation at electrode interfaces and of the unsuspected (until recent years) role it plays in properties of the double layer and in determining the potential profile at charged metal surfaces in solution.