This work describes the reactivity of the char residue in spent Chattanooga Oil Shale. The process scheme investigated was a two-step process. The first step in the process was a pyrolysis (or retorting) process in which experiments were conducted at five different heating rates using a thermogravimetric method. The second step began after a period of temperature soaking and involved the gasification of the carbon in the spent shale from the pyrolysis process. A sample of oil shale obtained from an outcrop of Devonian Shale near New Market in Madison County, Alabama, ground to (-150 200 and -100 150 US mesh), was used in this investigation. The effects of particle size, heating rate during pyrolysis, temperature, and gas environment on the weight loss of the oil shale were studied. A Fischer Thermal Analyzer was used to determine the reactivity of the spent shale at atmospheric pressure to oxygen in an air/N/sub 2/ mixture and to CO/sub 2/. Reaction temperatures were from 700 to 1080 K. It was found that the reactivity of this shale increased with increasing heating rate during pyrolysis up to a heating rate of 10/sup 0/C/min, beyond which it started decreasing. It was also found that the reactivity of this shale increased with increasing temperature within the experimental range studied. Furthermore, the particle size of -150 200 US mesh was more reactive than the -100 150 US mesh size. The oxidation reactions between residual char and air were consistent with zero order reaction with respect to carbon and first order reaction with respect to oxygen content in the gas. The activation energy in air for -150 200 US mesh was found to be 17,600 cal/mole, a value comparable with the literature for other oil shale. The unreacted-core-shrinking model was found to give a good fit to the kinetic data collected in this experimental work. 58 references, 33 figures, 16 tables.