The activity of exfoliated MoS2 in hydrodesulfurization of dibenzothiophene (DBT) was compared to crystalline MoS2, molybdenum naphthenate (MoNaph) derived MoS2 and ammonium heptamolybdate (AHM) derived MoS2. The prepared catalysts had significantly different morphologies, as described by the crystallite stack height and slab length, measured by both XRD and TEM. These data were used to estimate the fraction of rim and edge sites in the crystallites. The DBT turnover frequency (TOF) was highest on the exfoliated MoS2, whereas the selectivity for hydrogenolysis and hydrogenation reactions was shown to correlate with the fraction of rim or edge sites. Selectivity for hydrogenolysis increased as the fraction of edge sites increased. (C) 2006 Elsevier B.V. All rights reserved.