This project was designed to explore the suitability of using fluorinated inorganic materials as solvents for in situ mining of thin seamed, heavily overburdened coal; to build a data base for the selection of an inorganic solvent for use in coal cleaning; and to determine if fluorinated solvents will reduce the organic and inorganic sulfur contents of coal as well as to lower the ash content. The coal samples were combined with pure solvent and with aqueous solutions at atmospheric pressure and at increased pressure. The increased pressure experiments are important because they duplicate the conditions anticipated for an in situ cleaning and mining operation. Trifluoroacetic, difluorophosphoric (phosphorodifluoridic), and trifluoromethane-sulfonic acids were found to be effective for cleaning high-sulfur, high-ash coal at 300 degrees c and at atmospheric pressure. At pressures up to 20,000 psi the effectiveness of these reagents is not decreased.