Experimental data are reported on the extents and rates of removal of impurities from a low-grade, low-rank South Australia lignite by thermal treatment of coal-water slurries in the temperature range 250-3S0“C, Removal of up to 80% of the water, 50% of the oxygen, 40% of the organic sulfur. 60% of the sodium chloride, and 30% of the “ash” constituents has been achieved, with a coal product yield of about 80% (dry, mineral-matter-free basis), containing over 98% of the original coal energy. Process thermal efficiency is estimated to be ∼95%. A distributed activation energy model provides a satisfactory fit to experimental data for the evolution of volatile species.