To evaluate the hydrogen donating ability of solvent for coal liquefaction, the liquefactions of Taiheiyo coal (Japanese subbituminous coal) and Yallourn coal (Australian brown coal) have been carried out in a 500 ml autoclave at 430–450°C under high pressure of hydrogen or nitrogen using a red mud—sulfur catalyst in the presence of different kinds of hydrogen donor solvents such as tetralin, decalin, methyl substituted tetralins and naphthalenes, etc. Liquefactions of Taiheiyo coal and Yallourn coal using hydrogen donor solvents such as tetralin or methyl substituted tetralins showed higher conversion and yield of SRC than that obtained using decalin. On the other hand, to estimate the effect of the hydrogen donor solvent, ab initio SCF molecular orbital calculation for several solvent molecules, such as tetralin, decalin, naphthalene and their methyl substituted homologues, has been applied. Calculated reactivity indices, for example, frontier electron density of hydrogen atoms in the solvent molecule and atomic orbital bond population of CH bond, were discussed and compared with the experimental results.