This volume continues the development of the Modern Aspects series in the electrochemical field. The series is now 18 years old, and it is relevant to note the degree of evolution that electro chemistry has undergone during this time, for it affects the character of the articles chosen. The trend is towards development of inter disciplinary areas of electrochemical science, with full stress upon the many directions of applications of knowledge of electrode processes. The degree of import which should be attached to electro chemical science arises from the changes in technology which must be made during the next few decades. These clearly involve a massive electrification and the gradual elimination of the present fossil fuel economy, for both ecological and economic reasons. Research on the fundamental aspects of the field-slow in development to a standard-must be promulgated, but its justification is the modern provisionofa basis for the needed future electrochemical technology. One vast area of potential application of electrochemical concepts is omitted by the present attitude. It is, of course, the electro biological aspect, perhaps, finally, the largest area of all for fruitful applications. These concepts are reflected in the editors' choice of chapters. Quantum mechanical descriptions of surfaces must be bravely faced. Oscillatory aspects of electrochemical systems are often met in nature and demand attention at a fundamental level. Organic electrochemistry is in an ascending phase. With the electro biological v Preface vi article, we hope to stimulate a beginning of electrodic applications in this area.