The thermal stability and hydrogen permeability of Ni 42 Zr 30 Nb 28―x Ta x (x = 0, 7, 14, 21, 28) amorphous alloys have been studied in the present work. The substitution of Nb by Ta was found to be effective in improving the thermal stability of the Ni 42 Zr 30 Nb 28 amorphous alloy. The onset crystallization temperature of the Ni 42 Zr 30 Nb 28―x Ta x amorphous alloys was increased by 58 K from 807 K for Ta-free composition to 865 K for Ni 42 Zr 30 Ta 28 due to the Ta addition. The hydrogen permeability of the Pd-coated Ni 42 Zr 30 Ta 28 amorphous membrane was measured to be about 0.86 x 10 ―8 mol·m ―1 ·s ―1 ·Pa ―1/2 at 673 K, which is slightly lower than that of the Pd-coated Ni 42 Zr 30 Nb 28 amorphous membrane. The hydrogen permeability of the Ni 42 Zr 30 Ta 28 amorphous membrane was revealed to be more temperature dependent in comparison to that of the reference membrane. The higher thermal stability combined with good hydrogen permeability give rise to the possibility of the practical use for Ni 42 Zr 30 Ta 28 amorphous alloy as a dense metal membrane operating at higher temperatures.