This paper addresses the evolution of defects introduced by hydrogen implantation into (100) Si as a function of hydrogen dose and annealing temperature. The implant disorder and its correlation with the hydrogen profile were studied using Rutherford backscattering and channeling, secondary ion mass spectroscopy, cross sectional electron microscopy and scanning electron microscopy. Cavities were formed at intermediate doses ∼ 3×10 16 cm -2 after anneals at temperatures T > 600°C. Strain fields around defects at the cavities essentially anneal out at temperatures exceeding 750°C. At such temperatures, all the implanted hydrogen diffuses out of the samples, leaving a band of faceted nanocavities in good quality crystalline Si.