The use of molybdenum hexacarbonyl, Mo(CO)(6), an effective catalyst precursor for coal liquefaction even in the absence of added liquids or special impregnation procedures, was studied in solvent-free microautoclave experiments. The activity of the catalysts formed from Mo(CO)(6), both for liquefaction of a Blind Canyon bituminous coal and for methanation of CO in the absence of coal, was a function of activation conditions and reaction parameters. The catalysts were characterized by X-ray diffraction and other methods. Decomposition of Mo(CO)(6) in the absence of sulfur led to an active form of molybdenum carbide. The use of H2S, the preferred sulfur source, promoted the decomposition of Mo(CO)(6), led to MoS2, and promoted coal liquefaction. Pressure/temperature data recorded throughout the microautoclave experiment were used to determine the onset of catalytic activity for methanation of the CO released from Mo(CO)(6) upon decomposition in the absence of coal. Methanation activity was seen at temperatures as low as 280 degrees C. However, a sharp increase in rate occurred at 340 degrees C. When the catalyst was formed in the presence of coal, rapid hydrogen uptake began at a slightly higher temperature (370 degrees C). The conversion of coal to products soluble in tetrahydrofuran correlated strongly with the initial rate of gas uptake. The cyclohexane conversion of coal was also catalyzed.