A variety of hydrocarbons were efficiently oxidized to the corresponding carbonyl compounds in good yields at the ambient temperature with a Schiff base Mn(III) complex as catalyst in the presence of 30% hydrogen peroxide. The oxidation took place selectively at the benzylic C-H bond through a Mn(V)-oxo intermediate. The influence of product yield as a function of solvent, temperature, catalyst concentration and reaction time was evaluated. The reaction is simple, clean and moderately high yield and generates water as the only by-product.