In this study, we tried hydrocracking of vacuum residue into lighter liquid oils using dispersed colloidal catalysts composed of nanosheet-structured WS2 materials. The vacuum residue of API gravity = 2.3 degrees was used as a reactant and hydrocracking reactions were performed in an autoclave batch reactor under 400 degrees C and the initial H-2 pressure of 70 bar. Both single and multi-layer WS2 nanosheet catalysts were tested and their activities were compared with those of bulk WS2 and MoS2 catalysts. The single-layer WS2, which was the highest in specific surface area (97.6 m(2)/g) due to its smallest particle size, showed the best performances in commercial fuel fraction yield (45.4 wt.%), C-5-asphaltene conversion (75.3%), API gravity of liquid product (13.8 degrees), and metal removal activity. To characterize the physicochemical properties of catalyst, various characterization techniques were applied, including transmission electron microscope (TEM), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) analysis. In addition, to assess the qualities of hydrocracking products, we carried out API gravity measurement, inductively coupled plasma-mass spectrometry (ICP-MS), and simulated distillation (SIMDIS) analysis. (C) 2014 Elsevier Ltd. All rights reserved.