The processing of coal:phosphoric acid mixtures using mild temperature (932-degrees-F) fluidized bed conditions is presented. Phosphoric acid promoted the desulfurization of the bituminous coals, producing chars that contained less than 20% of sulfur originally in the coals. Gaseous H2S was the primary sulfur-containing gaseous product. Pyritic sulfur was eliminated from the coal at a temperature as low as 410-degrees-F, whereas about 70% of the organic sulfur was removed from the coal at 932-degrees-F. In comparison with literature data, organic sulfur remaining in the char is suggested to contain thiophenic speciation. Phosphoric acid also decreased greatly the swelling character of the coals, and altered dramatically the yields of gas, condensate and char relative to that obtained during the processing of coal without acid.