The present review analyses the literature of the ternary sulfides hydrotreating catalysts, with emphasize on the HDS model reactions. Different classes of mixed sulfides are considered, such as Chevrel phases, chromium thiospinels, or pentlandites. Experimental difficulties of such studies are extensively discussed. A tentative of comparison on a common basis of thiophene HDS activity at 573 K and 0.1 MPa is undertaken for the results obtained by different authors. It has been shown that the thiophene HDS activity of ternary sulfides does not correlate with the mean metal-sulfur bonding energy in them, obtained by averaging of the energies for the corresponding binary sulfides. A rough correlation can nevertheless be constructed from the available literature data, relating the mixed sulfides HDS activity to their mean electronegativity. (C) 2007 Elsevier B.V. All rights reserved.