It has been found that the rate of hydrogen peroxide consumption in an alkane oxidation by the "O-2-H2O2-nBu(4)NVO(3)-pyrazine-2-carboxlic acid" reagent in acetonitrile is noticeably lower in the presence of an alkane than in its absence. This paradoxical phenomenon at the first glance can be explained if we assume that acetonitrile used as a solvent is efficiently oxidized by the system in the absence of alkane. This oxidation is depressed by alkane additive due to the competition between the alkane and acetonitrile for the active hydroxyl radicals efficiently generated by the reagent. It has been also shown that the H2O2 decomposition in the presence of an alkane occurs as a radical non-chain process. (C) 2004 Elsevier B.V. All rights reserved.