Interaction between atomic hydrogen and pyrolytic graphite is investigated by thermal desorption spectroscopy, atomic force microscopy, and scanning tunneling microscopy. After exposure in an atomic hydrogen flow, the initially smooth graphite surface becomes rough, with a height difference of several nanometers. When heated, the samples release hydrogen and their surface is smoothed out, showing monolayer-deep etch pits. After multiple sorption-desorption cycles, both the linear sizes and the depth of the pits increase.