Reactions of 1,2-(1,1’-)dinaphthylethane (DNE) and 1,2-diphenylethane (DPE) in a hydrogen donor solvent in the absence or in the presence of highly dispersed catalysts such as Mo(CO)(6)-S and Ru(acac)(3) were carried out at 658 or 698 K under a hydrogen atmosphere in order to investigate quantitative hydrogen transfer process in the cracking of C-C bond in coal. Dinaphthylethane mainly produced 1-methylnaphthalene, and diphenylethane afforded benzene, toluene, and ethylbenzene as the major low molecular weight products. In addition, hydrogenation of DNE and DPE occurred. In the absence of a catalyst, more than 70 mol % of hydrogen was transferred from the hydrogen donor solvent. In the presence of Mo and Ru catalyst, the hydrogen required for stabilizing free radicals and hydrogenating aromatic rings was predominantly derived from gas phase without or with a small amount of the solvent. However, the amount of hydrogen transferred from gas phase considerably decreased and the amounts of hydrogenated products and decomposed products of DNE and DPE lowered with increasing concentration of the hydrogen donor solvent even with the dispersed Mo or Ru catalyst. The hydrogen donor solvent retarded the catalyzed cracking of DNE and DPE because of competitive adsorption of the model compound and the hydrogen donor solvent on the catalyst surface.