We have bombarded single crystal (100) and (111) silicon with a hydrogen ion beam produced by a Kaufman ion source. A range of dose rates from 0.2–2.0 mA/cm2, bulk sample temperatures from 35°–350° C, and doses of 2×1017, 2×1018, and 2×1019 ions/cm2 at maximum ion energies of 1600 eV was explored. Transmission electron microscopy and electron spin resonance measurements were used to characterize the bombarded samples. Extensive microstructural modifications occur as a result of hydrogen ion bombardment; the orientation, size, density, and distribution of the features which form vary as a function of crystal orientation, dose rate, bulk temperature, and total dose. Electron spin resonance studies indicate no detectable change in the number of occupied unpaired electron spin states occur in conjunction with this damage.