The effectiveness of several additives to inhibit the self-heating of coal was evaluated in the Bureau of Mines adiabatic heating oven. Aqueous solutions were applied to a bituminous coal with a high spontaneous combustion potential, and the minimum self-heating temperatures (sht's) of the dried coal-additive mixtures were determined. The relative effectiveness of the additives was determined by the observed changes in the minimum sht's of the mixtures compared to the untreated coal and a coal-water blank. The relative effectiveness of the additives within a group of coal- additive mixtures with the same minimum sht was determined by the time required for the sample temperature to reach 150 deg c. Sodium nitrate, sodium chloride, and calcium carbonate were found to be the most effective inhibitors, followed by ammonium dihydrogen phosphate, calcium chloride, ammonium chloride, sodium acetate, and potassium chloride. Two additives, sodium formate and sodium phosphate, promoted the self-heating process. Differential scanning calorimetry experiments on the coal-additive mixtures showed that reactions occurred between the coal and some of the additives, but these reactions did not influence the self-heating process.