Underground coal pyrolysis is a process similar to in situ oil shale production wherein heat is applied to deep coal formations to produce light hydrocarbons. Like enhanced coal bed methane, the injection of CO2 post thermal treatment can improve hydrocarbon recovery and serves as a means of carbon sequestration. Little information exists pertaining to coals pyrolyzed to temperatures expected with this process. This work examines the development of meso- and micropores and their influence on methane and carbon dioxide adsorption and permeability on a thermally treated Utah bituminous coal. Residual tars were found to affect the pore size distributions in pyrolyzed coals. Generally, with increasing treatment temperature, there are more meso- and micropores. A correlation was established between the prevalence of mesopores in pyrolyzed coals and adsorption and, to a lesser extent, permeability. The treatment temperature of this particular coal is directly related to the amount of CO2 said coal can store and how the plume of injected CO2 moves through the formation.