Some time ago a group of present and former collaborators of Professor John O'M. Bock ris, following a suggestion by Professor J. D. Mackenzie (Los Angeles), conceived the idea of an International Symposium devoted to reviewing the active and developing aspects of the science of electrochemistry. From this beginning has sprung the "Electrochemistry Symposium-The Past Thirty and the Next Thirty Years," which took place at Imperial College, London, from April 3-6, 1975. The plan for this symposium is unusual, since it features pairs of invited addresses, one to summarize the "state of the art" and the other to suggest directions for future re search in particular aspects of electrochemistry. This volume of proceedings gives these papers in their fmal, considered, and fully referenced form, arranged in the sequence of their delivery at the symposium. Also in cluded are introductory addresses given by Professor Ubbelohde, Professor Frumkin, Dr. Egan, and Dr. Inman. Both aspects of nearly every topic, plus the discussions, are integrated in a Report or Summary. A synopsis of the matters raised at the symposium and prepared by Professor John O'M. Bockris closes this volume. The cooperation of Plenum Press, New York, is gratefully acknowledged."