In an acidic media, the polarogram of I-nitroso 2-methylindoline shows a 4-electron cathodic wave. When carried out in buffered acetic acid preparative electrolysis at different ekctrodes lead to the expected l-amino 2-methylindoline. On the contrary, when sulfuric acid is the electrolyte, a mixture of the latter hydrazine and Zmethylindoline is obtained. Formation of the secondary amine can be explained as follows: (i) I-njtroso 2-methylindoline + H + + 2-methylindoline +NO *, (ii) l-amino 2-methylindoline + NO+ + 2-methylindoline + N30 + H+. Kinetic measurements ascertain the validity of these assumptions. Besides, the behaviour of two other secondary nitrosamines has been rapidIy studied. RdsnmQ-En milieu acide, le polarogramme de la nitroso-1 methyl-2 indoline prkente une vague de rtiuctjon a 4F par mole. Les Clectrolyses preparatives, r&Ii&es en tampon adtique sur diff&enles Clectrodes, conduisent B I'amino-1 methyl-2 indoline attendue. Par contre, en milieu sulfurique. on obtient un melange de I'hydrazine prktidente et de mdthyl-2 indoline. La formation de l'amine secondaire s'explique par I'intervention des deux reactions suivantes: (i) nitroso-1 methyl-2 indoline + H+ + methyl-2 indoline + NO+ (ii) amino-i mdthyl-2 indoline + NO+ + mdthyl-2 indoline + N, 0 + H +. L'ttude cindtique confirme la validitd du modble propost. Le cas de deux autres nitrosamines secondaires est rapidement examirk