Catalysis by CaO, CaCO3, and CaSO4 of the oxidation of a well-defined, high-purity synthetic char, Spherocarb, was investigated at low reaction temperatures using thermogravimetric analysis. results indicate significant catalytic effects-up to a 160-fold increase for CaCO3 catalysis, 290-fold increase for CaSO4, and up to 2700 times for CaO. Oxidation rates were likewise measured for fresh, demineralized, and Ca-loaded chars prepared from Beulah-Zap lignite coal in a flat flame burner at 1473 K. The oxidation rates of CaO-catalyzed Spherocarb and Zap char are the same within experimental error, suggesting that the high reactivity of the Zap char is due in large part to catalysis by CaO. It was also found that chlorine added to Ca-loaded char had a negligible effect on its low-temperature reactivity.