During 1980 and 1981 the Laramie Energy Technology Center (LETC) conducted a post-burn study at the Hanna II, Phases 2 and 3 underground coal gasification (UCG) site, Hanna, Wyoming. This report contains a summary of the field and laboratory results from the study. Lithologic and geophysical well log data from twenty-two (22) drill holes, combined with high resolution seismic data delineate a reactor cavity 42.7m (140 ft.) long, 35.1 m (115 ft.) and 21.3 m (70 ft.) high that is partially filled with rubble, char and pyrometamorphic rock. Sedimentographic studies were completed on the overburden. Reflectance data on coal samples within the reactor cavity and cavity wall reveal that the coal was altered by temperatures ranging from 245/sup 0/C to 670/sup 0/C (472/sup 0/-1238/sup 0/F). Overburden rocks found within the cavity contain various pyrometamorphic minerals, indicating that temperatures of at least 1200/sup 0/C (2192/sup 0/F) were reached during the tests. The calcite cemented fine-grained sandstone and siltstone directly above the Hanna No. 1 coal bed formed a strong roof above the cavity, unlike other UCG sites such as Hoe Creek which is not calcite cemented. 30 references, 27 figures, 8 tables.