Oxidations of arylalkanes by (Bu4NMnO4)-Bu-n have been studied in toluene solvent : toluene, ethylbenzene, diphenylmethane, triphenylmethane, 9,10-dihydroanthracene, xanthene, and fluorene. Toluene is oxidized to benzoic acid and a small amount of benzaldehyde; other substrates give oxygenated and/or dehydrogenated products. The manganese product of all of the reactions is colloidal MnO2. The kinetics of the reactions, monitored by UV/vis spectrometry, show that the initial reactions are first order in the concentrations of both (Bu4NMnO4)-Bu-n and substrate. No induction periods are observed. The same rate constants for toluene oxidation are observed in neat toluene and in o-dichlorobenzene solvent, within experimental errors. The presence of O-2 increases the rate of (Bu4NMnO4)-Bu-n disappearance. The reactions of toluene and dihydroanthracene exhibit primary isotope effects : k(C7HS)/k(C7D8) = 6 (+/-1) at 45 degrees C and k(C14H12)/k(C14D12) = 3.0 (+/-0.6) at 25 degrees C. The rates of oxidation of substituted toluenes show only small substituent effects. In the reactions of dihydroanthracene and fluorene, the MnO2 product is consumed in a subsequent reaction that appears to form a charge-transfer complex. The rate-limiting step in all of the reactions is hydrogen atom transfer from the substrate to a permanganate oxo group. The enthalpies of activation for the different substrates;ire directly proportional to the Delta H-o for the hydrogen atom transfer step, as is typical of organic radical reactions. The ability of permanganate to abstract a hydrogen atom is explained on the basis of its ability to form an 80 +/- 3 kcal/mol bond to H-., as calculated from a thermochemical cycle. (This bond strength is slightly lower than given in earlier calculations.) Rates of H-. abstraction by (Bu4NMnO4)-Bu-n correlate with rates of abstraction by oxygen radicals.