Over the past decade, bipolar electrochemistry has emerged from relative obscurity to provide a promising new means for integrating electrochemistry into lab-on-a-chip systems. This article describes the fundamental operating principles of bipolar electrodes, as well as several interesting applications. The graphic, by François Mavré, shows the principle of operation of a bipolar electrode within a microfluidic channel overlaid on a background image of electrogenerated chemiluminescence from an array of 1000 bipolar electrodes.