The water-induced disproportionation of the electrogenerated superoxide ion (O-2(-)) in acetonitrile, dimethylformamide, and dimethyl sulfoxide media containing various concentrations of water as a Bronsted acid has been examined by UV-vis spectroscopy. Analysis of the kinetics as a function of O-2(-) and water concentrations and of the measurement time demonstrated that the disproportionation of O-2(-) by water in these media obeys a common mechanism : O-2(-) + H2O reversible arrow HO2. + OH- (k(1), k(-1)) HO2. + O-2(-) --> HO2- + O-2 (k(2)) (HO2., hydroperoxyl radical; HO2-, hydrogen peroxide anion). The solvent dependence of the obtained kinetic parameters of (k(1)/k(-1))k(2), k(1) and k(-1)/k(2) is discussed in terms of the solvation of O-2(-) and H2O as well as the effective acidities of H2O in different aprotic solvents.