Two coals lone subbituminous and one bituminous) have been hydrogenated without solvent under different experimental conditions. Tests without a catalyst were performed at 300, 350, and 400 degrees C with a hydrogen pressure of 5 or 10 MPa. Two Fe-catalyst precursors (FeSO4 and red mud) were tested at 10 MPa of H-2 and increasing the temperature range up to 500 degrees C in the case of the bituminous coal. The results indicate that mainly at 400 degrees C and 5 MPa of H-2 important repolymerization reactions take place in the subbituminous coal, generating a large macropore volume in the solid residues. In Fe-catalyzed processes, and independently of the catalytic precursor, 425 degrees C seems to be a critical temperature. At lower temperatures, the hydrogenation reaction is predominant and the residues show increasing open porosity, at higher temperatures and mainly at 500 degrees C, the repolymerization processes are predominant, obtaining lower conversion and less porous residues. The repolymerization reactions bring about a blockage of porosity in all pore ranges.