Exfoliation by hydrogen implantation of GaN grown on sapphire was successfully accomplished for the purpose of wafer bonding and layer transfer. Hydrogen ions were implanted at 60 keV, with low doses of 2.5 and 5.0x10(16) H-2(+)/cm(2). High resolution x-ray diffraction and cross-sectional transmission electron microscopy were used to investigate splitting kinetics. High temperature exfoliation (>400 degreesC) was determined to depend on the diffusion of hydrogen. Low temperature exfoliation (<400 degreesC) was found to be limited by the crystallinity of the GaN. Extremely defective GaN layers were unable to be exfoliated in this lower temperature regime which was attributed to hydrogen trapping from a high density of dislocations.