Dinuclear copper and cyclic trinuclear cobalt complexes with pyrazolate and OH- bridges are able to decompose dimethyldioxirane in acetone, triggering radical reactions. Some products of reactions between organic substrates (cyclohexene or ethylbenzene) or acetone with secondary radicals formed from dimethyldioxirane: hydroxyl, methyl and acetomethyl, were identified and quantified. Tested complexes were also able to homolytically decompose cyclic acetone triperoxide and the radicals formed induced homolytic oxidation of cyclohexene producing 2-cyclohexen-1-ol and 2-cyclohexen-1-one at moderate yield. (c) 2006 Elsevier B.V. All rights reserved.