Polymers are normally thought of as insulators. In the last few years, however, a rapidly advancing and changing field has developed which exploits the ability of certain polymers to conduct charge, in some cases electronically and in others by means of ions. Certain electrochemical processes of major present-day industrial importance depend on the presence of polymeric materials for their efficient operation. The chlor-alkali industry is a prime example. Exciting new power sources, in which polymers replace conventional electrodes and/or electrolytes, are being intensively developed. Re...