Anionic polymerization processes variously termed living, controlled, or immortal are used to synthesize polymers having a narrow molecular weight distribution and low polydispersity (1.5). These processes are so named because polymerization generally occurs by addition of monomer units to a constant number of growing polymer chains until all monomer has been consumed; if more monomer is added, polymerization resumes. These living anionic processes are necessarily limited to use with monomers that can polymerize by an anionic mechanism, but many commercially important monomers do not undergo anionic polymerization under convenient conditions. While living free radical polymerizations have been investigated for monomers that polymerize by a free radical mechanism, there remains a need for new initiators of free radical polymerization, and, particularly, for living free radical polymerization. This invention covers a new class of free radical initiators--transition metal superoxides--that have been unexpectedly discovered that can initiate free radical polymerization under conditions commonly used in free radical polymerization processes.