A series of laboratory experiments has been conducted at the Western Research Institute to simulate the underground gasification of Herrin No. 6 bituminous coal. The samples were provided by Peabody Coal Company from its River King 3 mine near New Athens, Illinois. The program was conducted under a cooperative agreement with the US Department of Energy. The series consisted of three bench-scale tests, in which 1.5-ft (46 cm) coal cubes were used, and a large block test in a pilot-scale reactor. The large block was 2 ft (60 cm) high, 2 fit (60 cm) wide, and 4.5 ft (140 cm) long. The weakly swelling coal was gasified using steam and oxygen ratios ranging from 0.5/1 to 2/1 (steam/oxygen by volume). A nitrogen and oxygen mixture (2/1 by volume, nitrogen/oxygen) was tested for comparison with the steam/oxygen tests. Gasification of the small blocks typically consumed 20 lbs (9 kg) of coal and gasification of the large block consumed 150 lbs (68 kg). Small changes in the gas heating values were noted at the different steam/oxygen ratios. However, all of the tests produced a gas with a nitrogen-free dry heating value near 200 Btu/scf (176 KJ/mol). 9 refs., 4 figs., 4 tabs.