A manganese(IV) complex with the macrocyclic nitrogen-containing ligand 1,4,7-trimethyl-1,4,7-triazacyclononane (L) [LMn(mu -O)(3)MnL](PF6)(2) catalyzes the effective (the turnover number reaches 2000) catalytic oxidation of alkanes with tert-butyl peroxide in acetonitrile at room temperature. The products are alkyl hydroperoxide, ketone (aldehyde), and alcohol. Admixtures of acetic acid accelerate the reaction and increase the yield of the products. The manganese(IV) complexes [Mn4O6(bpy)(6)](BF4)(4) (bpy is 2,2'-bipyridyl) and [Mn(salen)(mu -O)](2) (salenH(2) is N,N'-disalicylidene-1,2-diaminoethane) and the tetraphenylporphyrin derivative of manganese(III) act as catalysts of similar but much less efficient oxidation, whose rate is not affected by adding acetic acid. All reactions are nonstereoselective and, probably, begin with the attack of the tert-butoxyl radical at an alkane C-H bond.