Low-temperature oxidation of buckskin subbituminous coal and derived chars produced in ENCOAL process was studied in a small-scale reactor at several experimental conditions. The consumption of oxygen and the generation of carbon monoxide occurred concurrently, while the formation of carbon dioxide was observed after a decline in the formation of carbon monoxide. The rate of carbon monoxide formation appears to be dependent on the moisture content of the reacting air, the moisture content of char, and the conditions at which the char is prepared. For example, higher concentration of carbon monoxide was produced from the moist air reacting with moisture-enriched char samples than with the dry air reacting with the as-received sample. This suggests that water plays an important role in the production of carbon monoxide. The activation energies and the first-order rate constants for oxygen consumption were measured and values agreed well with those found in the literature. (C) 2004 Elsevier B.V. All rights reserved.