Unsupported nickel-molybdenum-tungsten sulfide catalysts were prepared from tri-metallic Ni-Mo-W alkyl precursors by in situ activation during the hydrodesulphurization (HDS) of dibenzothiophene (DBT). The tri-metallic Ni-Mo-W precursors were prepared by reaction of tetraalkylammonium thiomolibdotungstates salts, (R4N)(4)MoWS8 (where R=H, methyl, propyl, butyl, cetyl-trimetyl), with NiCl2 in water at a Ni/Mo(W) molar ratio of 2. These precursors are named Ni/(NH4)(4)MoWS8, Ni/[N(CH3)(4)](4)MoWS8, Ni/[N(C3H7)(4)](4)MoWS8, Ni/[N(C4H9)(4)](4)MoWS8, Ni/[N(C19H42)(4)](4)MoWS8 to give NiMoW-H, NiMoW-C-1, NiMoW-C-3, NiMoW-C-4 and NiMoW-C-C catalysts respectively. These catalysts exhibit a "Swiss-cheese"-like morphology, a wide distribution of specific areas (from 6.9-194.07 m(2)/g) and high content of carbon (C/Mo = 2.5-8.9). The in situ activation of these tetraalkylammonium thiotrimetallates precursors leads to a mesoporous structure with pore size ranging from 10-40 Angstrom and type IV adsorption-desorption isotherms of nitrogen. X-ray diffraction showed that the structure of unsupported nickel-molybdenum-tungsten sulfide catalysts corresponds to a typical structure of 2H-MoS2 poorly crystalline with low-stacked layers. The nature of the alkyl group strongly affects both the specific area and the HDS activity. The catalytic activity is strongly enhanced when using carbon-containing precursors; the NiMoW catalysts prepared by in situ activation present high HDS activity. The lowest specific area of the catalysts was observed for the NiMoW-H sample.