The second and final test in the Underground Coal Gasification of Steeply Dipping Beds (UCG-SDB) was completed in November 198~ on a site near Rawlins, Wyoming. The feasibility of steam/oxygen injection in both a slant injection well (Module 1) and a vertical injection well (Module 2) was investigated. Table I summarizes the production characteristics during the various test phases. Further details of the test can be found elsewhere [1-4]. The data from these test phases were analyzed, and empirical mathematical models were developed where applicable. The significance of these models is then explained in light of process chemistry, and thermodynamic and physical UCG-SDB process concepts .