The development of iron pentacarbonyl derived coal liquefaction catalyst is summarized. Iron pentacarbonyl derived catalyst is one of the most active catalysts for the hydroliquefaction of a variety of coal samples. When low sulfur content coal was employed, the addition of an equivalent amount of sulfur to iron was necessary in order to achieve high activity. The active species of iron carbonyl derived catalyst is attributed to pyrrhotite, some of which is of nanosize order as determined by XRD and Mossbauer spectroscopic investigation. Kinetic studies of coal liquefaction using iron carbonyl sulfur catalyst showed that the role of catalyst is to promote direct hydrogen-transfer process from gas phase to coal fragment radicals. This was also supported by the results of the liquefaction of coal in hydrogen donor solvent tetralin.