The effects of reaction temperature and the amount of metal on the hydrogenolysis of cation (CO2+ or Ni2+) exchanged Adaro subbituminous coal in tetralin with elemental sulfur were discussed. In comparison with the reactions of the demineralized coal with metallocene complex [(C5H5)(2)CO or (C5H5)(2)Ni] at 400-440 degreesC, the yield of residue decreased on the reactions of cation exchanged coals. It was clarified that the hydrogen transfer from gaseous hydrogen and tetralin to coal radicles by the catalytic activity of the sulfarized Co or Ni appeared significantly due to the fire dispersion of the Co2+ or Ni2+ into coal macromolecules through the ion exchange with carboxylic groups. Accordingly, the catalytic effect of exchanged Co or Ni to coal was superior to that of metal derived from (C5H5)(2)Co or (C5H5)(2)Ni. On the simultaneous hydrogenolyses of demineralized and cation exchanged coals, the upgrading of demineralized coal was enhanced by the catalytic effect of cation in the exchanged coal. Therefore, it is estimated that the amount of coal fed to cation exchange treatment can be reduced by the simultaneous reaction. (C) 2004 Elsevier B.V. All rights reserved.