Although permanganate has been one of the most widely used oxidizing agents in organic chemistry for many years, the mechanisms of its reactions are often not well-known. Perhaps the most studied of these are the addition reactions to alkenes, however, recent reports of rate-determining hydrogen atom abstraction in some hydrocarbon oxidations suggest this latter mechanism may also be widely applicable. In this regard, the well-known oxidative addition reaction of permanganate with acetylacetone (acac) to form the Mn(III)trisacetylacetone complex is of interest, since it involves formal loss of one hydrogen atom from each of the acac molecules. We have performed a detailed kinetic investigation of the kinetics of this reaction as a function of pH and isotopic substitution. The kinetic data can be explained in terms of the reactions of permanganate with the enol and enolate forms of the acac. The rate constant for direct reaction of permanganate with acac is too small to be determined in this system. The reaction presumably proceeds via rate determining cycloaddition to the enol and one-electron oxidation of the enolate anion. Direct hydrogen atom abstraction is not important in this case.