The steady expansion of interest in electrochemical science and technology creates the need for a monograph series of the highest standards for the experienced reader. The purpose of the Advances in Electrochemical Science and Engineering series is to provide high-quality advanced reviews of topics of both fundamental and practical importance. The current volume addresses issues of chemically modified electrodes. Whenever bare surfaces do not fulfill the needs required, their chemical modification is a most promising way out of the dilemma. Purposeful attachment of atoms, molecules or even whole (nano)particles to the surface allows one to tailor the electronic and structural properties of a surface and hence, its functionality over a wide range. In the five chapters of this volume, internationally renowned scientists describe, how to modify a surface and what to do with it.