With contributions from the most prominent experts around the world, this resource provides an accessible summary of electrochemical techniques and the applications of electrochemical concepts to molecular-level systems. It describes the most important electro-active functional supramolecular systems developed so far, including rotaxanes and catenanes as molecular machines and as elements for information processing; dendrimers as molecular batteries, sensors, light harvesting antennae, and drug delivery systems; and bio-hybrid devices.