Hydroconversion of Cold Lake Vacuum Residue (CLVR) in both batch and semi-batch slurry reactors using unsupported MoS2 catalysts is reported. The MoS2 catalyst precursors were added to the CLVR either as an aqueous solution of ammonium heptamolybdate (AHM) or as molybdenum chloride dispersed in reversed micelles that were stabilized in n-hexane using a surfactant. At the reaction conditions studied in both the batch and semi-batch reactors, the MoS2 catalyst prepared in the reversed micelles had lower coke yield (toluene-insoluble material), lower gas yield, higher liquid yield and higher H-2 consumption, compared to the AHM-derived MoS2 catalyst. The coke-catalyst mixture recovered after reaction, characterized by chemical and energy dispersive X-ray analysis, confirmed that most of the added catalyst was captured by the coke. Analysis of the coke by X-ray diffraction and transmission electron microscopy confirmed the presence of highly dispersed MoS2 that suggests the possibility of catalyst-coke recycle. (C) 2009 Elsevier B.V. All rights reserved.