Novel [Mn-III(amp)(bipy)(Cl)](1) (H(2)amp: N-(hydroxyphenyl)salicyldimine; bipy: 2,2'-bipyridyl) and [Mn-III(app)(bipy)-(Cl)](+) (2) (H(2)app: N-(hydroxyphenyl)pyridine-2-carboxaldimine; bipy: 2,2'-bipyridyl) complexes have been synthesized and characterized by physico-chemical methods. Complexes 1 and 2 have been employed as catalysts in the oxidation of both saturated and unsaturated hydrocarbons using tert-butylhydroperoxide (t-BuOOH). A mechanism involving formation of and transfer from a reactive highvalent Mn(V)-oxo species as catalytic intermediate is proposed for the catalytic processes.