The passivation of nickel in molten alkaline nitrites and the electrochemical dissolution of passive nickel have been studied at temperatures ranging from 234-306°C. The passivation potential is established both in the potentiostatic E/Z curvy and in the galvanostatic anodic potential build-up. The passive film corresponds to a nickel oxide which after oxygen saturation approaches NiOl.a. The average film thickness provoking the onset of passivity is about 10 A. The passive nickel dissolves spontaneously at a constant rate and its dissolution is accelerated by the anodic discharge of nitrite ion on the passive film. The latter process is characterized by a Tafel slope of 2.3 RTiF V. which is explained by a reaction mechanism in which the dissolution is determined by the decomposition of the intermediate formed in the initial electron-transfer step. The postulated mechanism also explains the various reaction products. R&urn&Etude, dans un domaine de temperatures compris entre 234 et 306"C, de la passivation du nickel dans les nitrites al&ins fondus et de la dissolution 6lectrochimique du nickel passif. Le potentiel de passivation s'bablit aussi bien dans les courbes potentiostatiques E/Z que dans le d&eloppement galvanostatique du potentiel anodique. Le WI-I passif correspond & un oxyde de nickel qui, apr&s saturation d'oxyg&ne, avoisine NiO,,,.