An iron(III) porphyrin complex with highly electron-withdrawing substituents on the porphyrin ligand efficiently catalyzes the hydroxylation of alkanes by H2O2 via enzyme mimetic oxidation reactions in aprotic solvent. An "isolated" high-valent iron(IV) oxo porphyrin cation radical intermediate, prepared in situ by reaction of the iron porphyrin complex with m-CPBA at -40 degrees C, is capable of activating C-H bonds of alkanes to give oxygenated products efficiently. The hydroxylating intermediate generated in the catalytic H2O2 reaction is evidenced to be the high-valent iron(IV) oxo porphyrin cation radical species.