The Idaho National Engineering Laboratory (INEL) has for several years conducted research in the area of coal bioprocessing. Fundamental and exploratory research has been directed toward the conversion of coal to cleaner fuels and the remediation of harmful byproducts of coal utilization. Specific research projects have involved coal depolymerization, coal solubilization, removal of organosulfur and pyritic sulfur from coal, the molecular biology of coal-modifying microorganisms, removal of ash-forming minerals from coal, conversion of coal combustion gases, and the development of novel coal bioreactors. Notable research accomplishments include elucidation of mechanisms by which microorganisms solubilize different portions of coal, discovery and characterization of microorganisms capable of depolymerizing macromolecular coal, discovery of microorganisms capable of removing organosulfur from coal, development of technologies critical to analyzing biologically mediated depolymerization and organosulfur removal, novel methods of pyritic sulfur removal, novel methods of removal (and conversion) of CO2, SOx, and NOx from combustion gases, and new technologies for bioconversion of waste gypsum generated in coal combustion gas scrubbers.