This book originated out of the papers presented at the special symposium, "Electrochemistry in Transition-From the 20th to the 21st Century," scheduled by the Division of Colloid and Surface Science during the American Chemical Society meeting in Toronto. The symposium was in honor of Professor J. O'M. Bockris, who received the ACS award on "The Chemistry of Contemporary Technological Problems" (sponsored by Mobay Corporation) during this meeting and who also reached his 65th birthday in the same year. The symposium was of a multidisciplinary nature and encompassed the fields of theoretical and experimental elec trochemistry, surface science, spectroscopy, and electrochemical technology. The symposium also had an international flavor in that the participants represented several countries Australia, Belgium, Canada, Chile, England, Japan, Korea, the Netherlands, Poland, Switzer land, Venezuela, Yugoslavia, and the United States. The symposium was graciously sponsored by the ACS (Petroleum Research Fund and Division of Colloid and Surface Science), Alcan International, Dow Chemical Company, EG&G, Electrolyzer Corporation, Exxon, General Electric Company, IBM, Institute of Gas Technology, International Association of Hydrogen Energy, Johnson Matthey, Inc. , Kerr-McGee Corporation, Medtronics, and Texas A&M University (Center for Electrochemical Systems and Hydrogen Research and the Hampton Robinson Fund). The "theme" of the papers presented at the symposium covered not only significant contributions made to electrochemistry in the twentieth century, but also "New Horizons in Electrochemistry" for the twenty-first century. Thus, the scientists who presented papers were invited to contribute chapters to this book, having the same titles as the symposium.