It has been demonstrated in our laboratory that the transition metal complex ((2S,8R)-5-amino-2,8-dibenzyl-5-methyl-3,7-diazanonanedioato)copper(III) (1) is capable of mediating nonrandom double strand cleavage of plasmid DNA. Double strand DNA cleavage is thought to be a biologically significant source of cell lethality and is apparently an important mode of action for both the bleomycin and enediyne classes of antineoplastic agents. We present here the synthesis and characterization of 1 along with mechanistic studies of its DNA scission chemistry. Complex 1, upon reduction to the Cu(I) state in the presence of O-2, generates O-2(-) (HO2) and O-2(2-) (H2O2) which react to produce hydroxy radical through the Haber-Weiss reaction. Hydroxy radical is known to abstract hydrogen from deoxyribose, leading to strand scission, release of base propenals, and formation of abasic sites. The pseudo first order kinetics of single strand breakage (t(1/2) = 34 min), double strand breakage (t(1/2) = 21 min), and base propenal formation (t(1/2) = 100 min) have been measured. Base propenal release is therefore kinetically distinct from strand scission, ruling out mechanisms which invoke concerted base propenal formation with strand scission.