Abstract: The wettability and interfacial characteristics of molten Zr₅₅Al₁₀Ni₅Cu₃₀ metallic glass brazing alloy on polycrystalline α-Al₂O₃ and ZrO₂ substrates were studied using a modified sessile drop method.The results show that the wettability of the Zr₅₅Al₁₀Ni₅Cu₃₀/α-Al₂O₃ system is excellent with the final contact angles approaching zero degree at 1 133-1 193 K.However, the wettability of the Zr₅₅Al₁₀Ni₅Cu₃₀/ZrO₂ system is poor, but it can be progressively improved with the elapse of time during the isothermal dwelling in the temperature range of 1 133-1 253 K.A certain extent of interfacial reaction happens in both systems.The investigation on the spreading kinetics and interfacial microstructure indicates that the adsorption of the active atoms such as Zr at the interface, particularly at the triple junctions, plays a key role in determining the wettability, whereas the contribution of the interfacial reaction is relatively minor.