Ionic liquids have many important applications as chemical reaction media and in systems that depend on the transport of charge or redox equivalents. Pulse radiolysis is a powerful technique for measuring fast reaction kinetics, particularly redox processes. We have been using pulse radiolysis techniques to study reactions in ionic liquids. The radiation chemistry of ionic liquids differs from that of conventional liquids in several ways that can be traced back to their unique physical properties. Supported by the U.S. Dept. Of Energy, Basic Energy Sciences, Chemical Sciences Division, under contract DE-AC02-98-CH10886.