Two Bulgarian high sulphur coals, i.e. subbutiminious (Pirin) and lignite (Maritza East), and one Turkish lignite (Cayirhan-Beypazari) are biodesulphurized on laboratory scale. Prior to biotreatments coal samples are chemically treated to be demineralized and depyritized. Due to chemical treatments total sulphur desulphurization in the range of 25.3-54.2% is achieved. Inorganic sulphur (pyritic and sulphatic) is mainly attacked. Pyritic sulphur desulphurization varies in the range of 59.6-77.4%. The white rot fungi ""Phanerochaeta chrysosporium" - ME446 and the thermophilic and acidophilic archae "Sulfolobus solfataricus" - ATCC 35091 are the microorganisms applied in the biodesulphurization processes. Better biodesulphurization is attained for coal samples treated with "P. chrysosporium". Maximum effect of biodesulphurization due to further total sulphur decrease (Delta S-t) of 24.2% and further organic sulphur decrease (Delta S-o) of 23.8% is registered after fungi biotreatments on deminerilized and depyritized coals. By "S. solfataricus" maximum further Delta S-t and Delta S-o biodesulphurization effects of 16.9% and 18.3%, respectively, are determined. AP-TPR device coupled with different detection systems (MS and TD-GC/MS) gives us opportunity to track organic sulphur alterations as a result of the applied biotreatments. By AP-TPR "off-line" TD-GC/MS an improved organic sulphur information is obtained due to specific sulphur sorbent application. A broad range of sulphur-containing organic compounds as well as SO2, COS and CS2 are identified and quantitatively interpreted. (C) 2012 Elsevier Ltd. All rights reserved.