This study provided a thorough investigation of surface blistering and exfoliation behavior in germanium substrates with different crystal orientation, which is crucial for understanding the mechanism of smart-cut process in the fabrication of germanium-on-insulator. Two hundred-kilo-electron-volt H2+ ions with a fluence of 2.5 × 1016 ions/cm2 were implanted into (100)-oriented, (111)-oriented, and (110)-oriented n-type germanium wafers. Following ion implantation, the post-annealing treatments were conducted to drive the formation of blisters and craters in germanium. In conducting the characteristic analysis, hydrogen depth profiles were measured using SIMS. In situ optical microscopy observation was performed to measure the threshold temperature and onset time of the blisters and craters. Cross-sectional transmission electron microscopy was also employed to examine the micro-structural properties of hydrogen-induced radiation defects in the specimens. The kinetics of the thermally activated blistering process was also analyzed to estimate the effective activation energy for blister and crater formation. The results revealed that an obviously different morphology of the optically detectable blisters and craters can be identified in Ge(100), Ge(111), and Ge(110) specimens. Substrate orientation of germanium also makes a great impact on the blistering threshold temperature, the onset time and activation energy for blister and crater formation, and the development of hydrogen implantation-induced micro-cracks. Copyright © 2014 John Wiley & Sons, Ltd.