Ammonium thiomolybdate [(NH4)(2)MoS4, ATM] and tetrabutylammonium thiomolybdate were used as precursors to prepare MoS2 catalyst. The precursor was decomposed in situ under hydrogen pressure and in the presence of decalin solvent during the hydrodesulfurization (HDS) of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). The as-synthesized catalysts and the spent catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and BET specific surface area measurements. All catalysts demonstrated type IV adsorption-desorption isotherms of nitrogen, and a mesoporous structure with a pore size of 3-4 nm. X-ray diffraction showed the structure of MoS2. The effect of water addition was investigated. The results revealed that the MoS2 prepared from ATM precursor showed a large increase in surface area and change in morphology when water was added, but for the MoS2 prepared from TBATM precursor, water had a negative effect. The catalytic activity is enhanced when the catalyst promoted with Co or Ni is used. The catalyst from ATM efficiently reduces sulfur content in straight run gas oil (SRGO) and light cycle oil (LCO).