Metal-superoxo intermediates have been invoked as reactive species in C-H bond cleavage of substrates by oxygenase enzymes. In this work, we have shown the first structurally characterized end-on chromium(III)-superoxo complex, [Cr-III(14-TMC)(O-2)(Cl)](+), which was synthesized by reacting [Cr-II(14-TMC)(Cl)](+) with O-2. The Cr(III)-superoxo intermediate has shown reactivities in C-H cleavage of alkylaromatics via a H-atom abstraction mechanism.