Abstract: New mediators for use in laccase-mediator systems (LMS) are disclosed. The mediators enhance the activity of enzymes exhibiting laccase activity and can be used, for example, to bleach a dye in solution, to oxidize an appropriate compound, or to initiate vinyl or phenol polymerizations. A composition comprising an enzyme exhibiting laccase activity and an enzyme enhancing agent (also referred to as a mediator or an activating agent) is also disclosed. A process for oxidizing a substrate that comprises treating the substrate with a composition comprising an enzyme exhibiting laccase activity and an enzyme enhancing agent is also disclosed.