The ambient effects on the interactions at the Ni/Al and Pt/Ni interfaces have been studied using the Pt/Ni/Al/SiO2/Si structure. A suppressed diffusion of Al in Ni by oxygen is predicted by our surface potential model and confirmed in this study. For the Pt/Ni interface, on the other hand, oxygen is expected to enhance the diffusion of Pt in Ni but suppress that of Ni in Pt. The observed reduction in interdiffusion between Ni and Pt by oxygen indicates a dominant role of the more electronegative metal Pt in determining the ambient effects observed. Such a dominance of the more electronegative metal is consistent with all the earlier observations where the overcoating metal is the more electronegative and only its surface potential change induced by the ambient is considered in explaining and predicting the ambient effects for various systems.