The sulfur removal potential of the water-soluble fraction of fly ash in oxydesulfurization of coal was investigated using some high-sulfur Turkish lignites. The effects of the amount of fly ash used, temperature, partial pressure of oxygen and time were studied in the ranges 5-40 g, 403-498 K, 0.0-1.5 MPa and 15-90 min respectively. The extents of pyritic and organic sulfur removal and recoveries of coal and calorific value were investigated for each of these variables. Reactivity and some combustion characteristics (ignition temperature, end temperature of combustion and combustion rate) of original and desulfurized lignite samples were compared using combustion curves obtained from thermogravimetric analysis (t.g.a.) results. FT-i.r. spectroscopy was used to determine the effects of the desulfurization process on the coal structure. Copyright (C) 1996 Elsevier Science Ltd.