In general, ‘electrochemistry’ is a field that deals with heterogeneous electron transfer between metal electrodes and conductive liquid phase materials. The high selectivity and sensitivity of electrochemistry in aqueous solutions are applicable to many areas such as surface analysis and sensors. However, the effect of solid elastomers on electrochemistry is uncertain compared with well-known theory and applications in aqueous solution. In this book, the physical and chemical phenomena of the metal surface contacted with the elastomer and application of the faradaic reaction at elastomer-electrode interface were studied by amperometric and voltammetric methods. Chapter 1 provides an overview for methods of measurement and the relationship between electrochemistry and elastomers. In Chapter 2, the contact electrification and mechanochemistry at elastomer-gold interface and the origin of chemical reactions occurring at that time are electrochemically analyzed. In Chapter 3, a sensing platform consisting of a viscoelastic hydrogel microstructure and an ITO working electrode is suggested, and a sensor sensitive to external stimuli such as pressure, chemicals, and temperature is implemented based on electrochemical reactions.