Different morphologies of oil-dispersed MoS2 catalysts were obtained by a ligand stabilization method using Mo(CO)(6) as a Mo precursor and trioctylphosphine oxide (TOPO) as a coordinating agent to identify the active site of MoS2 in the hydrocracking (HCK) of vacuum residue (VR). Transmission electron microscopy (TEM) and extended X-ray absorption fine structure (EXAFS) spectroscopy were used to obtain structural properties of the dispersed catalyst. It was observed that the MoS2 forms a nanoscaled mono layer from 5 to 10 nm in size. The effect of the oil-dispersed MoS2 catalysts having different morphology on the slurry phase HCK of VR was investigated at 673 K and 9.5 MPa H-2. The turnover frequency (TOF) of the dispersed MoS2 catalysts in the VR HCK was found to show a good correlation with the rim-site Mo dispersion of the MoS2 slabs based on the same metal loading of 0.113 mmol at 673 K and 9.5 MPa H-2. (C) 2018 Elsevier Inc. All rights reserved.