Tabas coal sample from Iran was desulfurized with combination of microwave irradiation and peroxyacetic acid washing in a batch reactor. The effect of irradiation time and power, peroxyacetic acid reaction time and temperature and particle size on reduction of sulfur was investigated. For microwaved/acid washed samples, depending on desulfurization conditions, the reduction in pyritic, organic and total sulfur ranged from 26 to 91, 2.6 to 38.4 and 17 to 65%, respectively. Microwave irradiation had positive effect on desulfurization with peroxyacetic acid. For < 300 mum size fraction, after irradiation, the reduction enhanced from 49.9 to 86.6% in pyritic sulfur, 23.8 to 35% in organic sulfur and 36 to 61.9% in total sulfur. FT-IR spectroscopy of coal structure before and after desulfurization has shown significant changes in the peak corresponding to pyrite whiles the bands related to coal organic matrix have not changed significantly. The results prove that this method can use as secure process on removal of inorganic and organic sulfur without destruction of coal organic matrix. (C) 2003 Elsevier Ltd. All rights reserved.