A substantial oxidative N-debenzylation reaction along with PhCH=O formation occurs from a hydroperoxo-copper(II) complex that has a dibenzylamino substrate (-N(CH2Ph)(2) appended as a substituent on one pyridyl group of its tripodal tetradentate TMPA (also TPA, (2-pyridylmethyl)amine)) ligand framework. During the course of the (L-N(CH2Ph)2)Cu-II(-OOH) reactivity, the formation of a substrate and a -OOH-derived (an oxygen atom) alkoxo Cu-II(-OR) complex occurs. The observation that the same Cull(-OR) species occurs from Cu-I/PhlO chemistry suggests the possibility that a copper-oxo (cupryl) reactive intermediate forms during the alkoxo species formation; new ESI-MS data provide further support for this high-valent intermediate. A net H atom abstraction chemistry is proposed on the basis of the kinetic isotope effect studies provided here and the previously published study for a closely related Cu-II(-OOH) species incorporating dimethylamine (-N(CH3)(2)) as the internal substrate;(27) the Cul/PhlO reactivity with similar isotope effect results provides further support. The reactivity of these chemical systems closely resembles the proposed oxidative N-dealkylation mechanisms that are effected by the copper monooxygenases, dopamine beta-monooxygenase (D beta M) and peptidylglycine-alpha-hydroxylating monooxygenase (PHM).