Hydrogen transfer behaviors of four Argonne coals with gas phase tritiated H-2 in thermal (non-catalytic) and catalytic reactions (in the presence of 3 wt% Pt/Al2O3) in temperature range from 250 to 400 degreesC have been investigated using a fixed-bed reactor. The result showed that the efficiency of hydrogen transfer reaction of coal with the gas phase in the thermal run increased with increasing oxygen functionalities, providing the indication that some oxygen functional groups have a role for effective promotion of hydrogen transfer reaction with the gas phase H-2 under mild condition. When the reaction was run in the presence of the catalyst, the efficiencies of hydrogen transfer reaction for the all coals, except for the POC coal, were significantly enhanced even at temperature as low as 250 degreesC. The results for the catalytic reaction have provided indications into the reactive sites (formation of free-radicals) in coal and patterns for coal matrix degradation reactions. (C) 2003 Elsevier Science Ltd. All rights reserved.