Structural studies of the growth of oxide film on the glass sealing alloy Ni42Cr6Fe under high temperature moist hydrogen atmosphere were observed by using SEM, TEM and X-ray diffraction techniques. At initial oxidizing stage, Cr 2 O 3 and spinel (Fe, Mn) Cr 2 O 4 were nucleated simultaneously. The former mainly grew intergranularly and the latter intragranularly. Then, the growth of oxide film was mainly of Cr 2 O 3 due to the selective oxidation of Cr. As oxidation goes on to a certain extent, the surface Cr depletes and the growth of oxide film changes into spinel as majority. Finally, the coarse spinel (Fe, Mn) Cr 2 O 4 will form at outer surface, the fine Cr 2 O 3 grains in the bed and the coarse spinel around fine Cr 2 O 3 will be matured in the middle part of oxide film.