Nanometer-sized particles of molybdenum oxide were thermally deposited and then sulfided on mica, MoS2, and highly oriented pyrolytic graphite (HOPG) to simulate MoS2 catalysts for the hydrodesulfurization reaction of petroleum. The topography of the particles observed by AFM reflected the interaction force dominant at the particle-substrate interfaces. Oxide particles ionically interacted with mica which restricted the mobility of the deposit and led to particles smaller in lateral dimension, whereas aggregated oxide was observed on the other non-ionic substrates. Basal-bonded MoS2 crystals were observed on the three substrates when sulfided at 673 K. [DOI: 10.1380/ejssnt.2003.80]