Abstract Autoxidation of 2-substituted anthranols to the corresponding anthraquinones in alkaline buffered aqueous dioxane (2:1 in vol) has been studied kinetically at 35 °C by means of the manometric method. The relative rate constants for the autoxidation of anthranyl oxide ions have been evaluated, in which dissociation of anthrones is taken into account. Application of substituent effect on the one-electron transfer to the oxide ion to the Hammett equation gives an average ρ-value of −1.5, which was little influenced by pH of the solution.