Catalytic coal gasification was stuided by the method of thermal desorption spectroscopy（TDS） under high vacuum condition. Charcoals of Jangsung coal(anthracite) and Tatong coal(bituminous coal) were used as carbonaceous material, and alkali metal salts such as K₂CO₃, Na₂CO₃, K₂SO₄, and mixed salt of K₂SO₄ and Na₂CO₃ as catalysts. CO₂ TDS pattern was obtained by heating sample to 1000 K after O₂ adsorption at room temperature. The activities of catalyst-unloaded sample and K₂SO₄-loaded sample were almost same, but poor. Samples loaded with K₂CO₃ and Na₂CO₃ showed the same characteristic peak at about 830 K, which was caused by active sites on the coal activated by catalyst. In case of the sample loaded with both K₂SO₄ and Na₂CO₃, the peak of 830 K was not shown in the first CO₂ TDS spectrum, but it appeared after repeating CO₂ TDS several times. Tatong coal was preferred to Jangsung coal in forming the active sites. Therefore, the mixed salt catalyst showed enhanced activity comparing with its constituent single salt, and Tatong coal was recommended for coal gasification.