This invention relates to the preparation and use of supported, manganese sulfide promoted molybdenum and tungsten sulfide catalysts useful for hydroprocessing processes, particularly hydrotreating. These catalysts are prepared by heating a composite of support material and precursor salt under oxygen-free conditions and in the presence of sulfur, wherein said precursor salt contains a thiometallate anion of Mo, W or mixture thereof and a cation comprising one or more promoter metals which are chelated by at least one neutral, nitrogen-containing polydentate ligand, and wherein said promoter metal comprises Mn alone or a mixture of Mn with Co, Ni, Zn, Cu or mixture thereof.