Electrochemical reduction of oxygen on a nickel electrode in alkaline solutions has been studied using the rotating ring-disk-electrode method. The change in the ratio of two possible reaction courses (uiz with or without intermediate formation of hydrogen peroxide) depends on the potential degree of electrode oxidation and the composition. Oxidation of the nickel electrode surface leads to considerable inhibition of oxygen reduction accompanied by increased hydrogen-peroxide yields. In LiOH solution the contribution of the reaction with intermediate hydrogen-peroxide formation is less, as compared with the KOH solution. The constants of individual reaction steps of the oxygen. reduction reaction have been calculated. A study has been made of the hydrogen-peroxide reduction; oxidation and catalytic decomposition on the nickel electrode. Hydrogen peroxide does not undergo decomposition. Increase in the oxidation state of the electrode surface inhibits hydrogen-peroxide reduction, but scarcely affects its electrochemical oxidation. R&u&-On 6tudi6 la r&hrction d'oxyg&ne sur des electrodes de nickel en solution alcaline aver une electrode tournante a disque avec anneau. La relation de deux possibles tours de reaction (avec et sans formation de HIOJ depend du potentiel, de l'etat d'oxydation de la surface et de la composition de la solution. L'oxydation de la surface freine la reduction d'oxygkne et augmente la formation de HtOp. En sohrtion de LiOH la contribution de la reaction avec formation de HiOr, eat moindre qu'en solution de KOH. Les constantes de vitesse de divers stadee de la &action ont 6t6 calc&es.
On a btudi6 la reduction, l'oxydation et la d&composition catalytique de F&,0, sur des 6lectrodes de nickel. Dans les conditions d'exp&ience choisies on n'observe pas de decomposition. L'oxydatian de la surface m&e a un ralentissement de la rCduction, mais n'aflecte pas la vitesse d'oxydation de HtOl.