The stereoselective copper-mediated hydroxylation of intramolecular C H bonds from tridentate ligands is reinvestigated using DFT calculations. The computational study aims at deciphering the mechanism of C H hydroxylation obtained after reaction of Cu(I) precursors with dioxygen, using ligands bearing either activated (L 1) or nonactivated (L 2) C H bonds. Configurational analysis allows rationalization of the experimentally observed regio-and stereoselectivity. The computed mechanism involves the formation of a side-on peroxide species (P) in equilibrium with the key intermediate bis-(μ-oxo) isomer (O) responsible for the C H activation step. The P/O equilibrium yields the same activation barrier for the two complexes. However, the main difference between the two model complexes is observed during the C H activation step, where the complex bearing the non-activated C H bonds yields a higher energy barrier, accounting for the experimental lack of reactivity of this complex under those conditions.