Abstract: The hydropyrolysis of organic matters was comparatively conducted over various catalysts including ZnCl₂, NiCl₂, Fe₂O₃, NaY and MoS₂ and the reaction mechanisms over different catalysts were then investigated. The results indicate that the yield and composition of liquid products from hydropyrolysis are related to the type of catalyst, though various catalysts do not have significant difference in the product biomarker parameters. Meanwhile, for the organic matters with different maturities and types, various catalysts are also quite different in their actual performance. The element analysis, infrared spectra and X-ray diffractograms of the solid residues illustrate that various catalysts are obviously different in the catalytic reaction mechanism. In comparison with NiCl₂, mass transfer is an important factor in the ZnCl₂ system, besides the catalytic cracking and catalytic hydrogenation. With Fe₂O₃ as the catalyst, the formation of H free radical by the adsorption of H₂ at the surface active O sites may promote the hydrogenation of organic matters. MoS₂ as the catalyst may involve two mechanisms, viz., the hydrogenation over transition metal Mo and the initiation of free radicals from H₂S intermediates.