Transition liquid phase (TLP) bonding has been conducted on a Hastelloy X using amorphous foil filler metals. The inserted fillers were made by rapid solidification of a Ni-15% Cr alloy containing 3 to 5 mass% boron as a melting point depressant. The microstructural change with isothermal bonding time from 2.4 to 38.4 ks was examined in the bond regions by optical microscopy and electron probe microanalysis (EPMA). An assessment of the bond strength was made by stress rupture tests performed at 1173 K. It was found that rupture strain and rupture life increased with increasing bonding time. A bond efficiency greater than 80 % was achieved when the bonding time was 38.4 ks.