Yields ofcis-1,2-cyclohexanediol formed by the reaction of methanol–water solutions of potassium permanganate with cyclohexene varied from nearly zero to a high of 84% as a function of stirring efficiency and dilution. This unusual effect is attributed to the formation of an intermediate hypomanganate ester ion which after formation may undergo reaction [1] with water to form the glycol or [2] with excess MnO4−to form higher oxidation products. The factor of increased stirring and dilution reduced localized excess of MnO4−and, thereby, minimized the contribution of reaction [2]. Addition of modest concentrations of methanol increased the yield, and this is attributed to enhanced solubilization and dispersion of the insoluble cyclohexene. Sodium hydroxide was beneficial to the reaction but only in low concentrations.