The main reason that graphite electrodes are used in electrolysis is that graphite is an excellent conductor. The structure of graphite is such that it has a large number of electrons floating freely between the different layers of atoms (graphite bonds are formed of only three out of the four electron shells of the carbon atom, leaving the fourth electron to move freely). These electrons act as a powerful conductor, enabling the electrolysis process to progress smoothly. In addition, graphite is economical, stable at high temperatures and hard-wearing. For all these reasons, graphite electrodes are frequently used in electrolysis.