The amount of hydrogen evolved from a coal during pyrolysis at atmospheric pressure in the presence of a coal hydrocracking catalyst can be used for estimating the activity of the catalyst for high pressure hydrogenation of coals, moreover, a linear correlation was observed between hydrogen evolution under atmospheric pressure and the catalytic activity of the catalyst for liquefaction under high pressures. The most active catalyst for liquefaction of Akabira coal was Fe₂O₃-SO₄^2-. In the liquefaction of Big Brown lignite at 450°C, MoO₃CoO/Al₂O₃ and MoO₃/TiO₂ showed high selectivity for liquid products while Fe₂O₃/MoO₃-SnO₂ and Fe₂O₃-SO₄^2- showed low selectivity for liquid products but high selectivity for gaseous products.