The treatment of the coal organic matter by ozone is shown by means of the chemical analysis and IR-spectroscopy to result in the redistribution of oxygen atoms in the functional groups. Based on the X-ray diffraction data, it has been shown that the change of the macromolecular organization of the coal organic matter under ozonization is due to the transformation of an amorphous phase, i.e. the formation of crystal associates in it, resulting from packing the plane aromatic fragments after their substituents have been separated. The kinetic analysis of the thermal liquefaction process of ozonized coal in tetralin under non-isothermal conditions indicates that successive liquefaction of the coal organic substance activated by ozone and a certain part of the non-activated coal does occur. The amounts of the coal organic matter activated by ozone and effective activation energy values of the thermal liquefaction process have been estimated. (c) 2005 Elsevier Ltd. All rights reserved.