Crystalline [LCoIII-OOR] complexes with strong-field ligands, L, afford ROO. and RO. radicals upon mild heating in solution. This fact allows oxidation of hydrocarbons by these complexes under mild conditions. The extent of hydrocarbon oxidation by discrete [LCoIII-OOR] complexes depends on the nature of L, the solvent, the temperature, and the presence of other M(II) ions. Such systems are catalytic in the presence of excess ROOH.