Tin-amalgams of varying concentrations were oxidized galvanostatically in O-01,0-10 and 2~00 N NaOH solutions at 25°C. For each amalgam and solution composition a number of constant polarizing currents were used and cyclization was repeated until the oxidation (reduction) features of the amalgam became apparent. Two different oxidation patterns were distinguished. The first describes the behaviour of all amalgams in O-01, O-1 N NaOH, and of concentrated amalgams in 2 N NaOH, and the second for the behaviour of dilute tin amalgams in 2 N NaOH solutions. The oxidation curves in O-01, O-1 N NaOH showed regions for the dissolution of the sodium amalgam formed during eathodization, for the charging of the anodic double layer, and for the formation of a Sn(OH), film on the surface of the electrode, before the evolution of oxygen. The oxidation curves of dilute Sn amalgams in 2 N NaOH showed a region of oscillations in potential and the development of an arrest for HgO. The relation between the current, i, and time of passivation, 7, was found to be log7= A -?zlogi, where A and zi are constants. The results indicate that the passivation of Sn amalgams in alkaline solutions is governed by the rate of metal atom diffusion to the electrode surface and by the physical and chemical properties of the oxide film formed at the interface. A. M. SHAMS EL DIN and L. A. KAMEL Einsetzen der Sauerstoffentwicklung. Die Oxydationskurven verdiinnter Amalgnme in 2 N NaOH wiesen ein Gebiet mit Potentialoszillationen auf, sowie die Ausbildung einer Stufe fiir HgO. Folgende Eteziehung existiert zwischen dem Strom und der Passivierungszeit 7 log 7 = A -n log i wobei A und n Konstanten sind. Aus den Ergebnissen kann geschlossen werden, dass die Passivierung von Sn-Amalgunen in alkalischen LBsungzn durch die Ditfusionsgeschwind:gkeit der Metallatome zur Elektrodenoberfllche und durch die physikalischen und chemischen Eigenschaften des gebildeten Oxyds hestimmt ist.