Comprehensive spectroscopic and electrochemical investigations of the interfacial structure of metal electrodes and self assembled monolayer (SAM) modified electrodes form the focus of this research project. In work supported by the Analytical and Surface Chemistry Program, surface Raman spectroscopy will be used to probe metal electrodes in situ and emersed under potential control. In addition, ultra high vacuum methods will be used to prepare model systems which mimic the behavior of these electrochemical interfaces. Surface Raman spectroscopy, as well as other surface spectroscopic probes, will be used to characterize these model systems. Electrode surfaces modified by organic overlayers will also be probed using these methods. A detailed understanding of the structure of electrochemical interfaces is crucial to the design of many electrochemical systems and sensors, ranging from fuel cells to environmental monitoring devices. The work supported here develops and applies methods for the structural characterization of these interfaces to a range of well controlled model systems. The information gained from these studies will be invaluable in a wide range of technological applications of electrochemistry.