Mixing a dinuclear CuII complex with an excess of primary or secondary amine in the presence of dioxygen with or without toluene yields N-oxyl radicals and CuI entities. The EPR spectra of these radicals clearly show their evolution from the initial to the final state. Under these mild conditions, it is not possible to obtain Tempo radicals, steric crowding impeding the approach of the corresponding amine into the CuII coordination sphere.