This project is in the general area of analytical and surface chemistry and in the subfield of electrochemistry. It contains five specific research thrusts: (1) Studies of electron transfer kinetics across well-defined Langmuir-Blodgett oriented molecular films; (2) Electrocatalysis using colloidal clay-supported electron transfer mediators; (3) Mechanistic studies of the electrocatalytic reduction of dioxygen; (4) Studies of polyoxymetallates as electrocatalytic reagents; and (5) Oxidative electrocatalysis using nitroxyl compounds. These studies address fundamental issues in heterogeneous electron transfer kinetics across membrane-like molecular structures, basic studies in the electrochemistry of dioxygen that are of prime importance to efficient fuel cell technology, and the development and evaluation of new catalytic systems with which the electrochemical production of desired materials can be made to proceed selectively and cost effectively. Realization of the goals of this project can be expected to enhance our understanding of the fundamentals of electron transfer processes at membrane-solution interfaces, which is essential to the development of biosensors, and to define new electrocatalytic systems with which economical electrosyntheses and the efficient interconversion of electrical energy and chemical energy can be facilitated.