The average structure of organic substances contained in Barzas coal has been constructed by means of a commercial molecular modelling package on the basis of kinetic investigations and structural group analysis of high-molecular products obtained by the process of coal non-isothermal liquefaction in a proton-donor solvent. This model structure has been optimized geometrically by minimization of its conformational energy. The established model structure corresponds to the mean formula C727H790N2S4O36 and to a molecular weight of 10,260 g/mol (amu). (C) 2004 Elsevier Ltd. All rights reserved.