The Si(111) 7×7 surface is exposed at room temperature to atomic hydrogen and studied with scanning tunneling microscopy (STM) and low energy electron diffraction (LEED) in ultrahigh vacuum. For increasing exposures, the LEED pattern of the surface changes in well defined steps to a 1×1 pattern. The STM images of the 1×1 surface appear rough and disordered. The 1×1 pattern and rough surface are consistent with an etching of several surface layers by the atomic hydrogen. Heating the 1×1 surface to 560 °C and cooling to room temperature produces a surface with a ×R30° LEED pattern. The STM images of this surface are consistent with a distribution of adatoms on an ideal Si(111) surface. Further heating results in a 7×7 surface. © 1997 American Vacuum Society.