Molybdenum (Mo) supported on aluminum-pillared clay (Al-PILC) and zirconium-pillared clay (Zr-PlLC) with contents of 0.6, 1.4 and 2.8 atoms of Mo/nm(2) were prepared and tested in the hydrogenation (HYD) of naphthalene (NP). It was found that the molybdenum sulfide (MoS2) catalysts supported on Zr- pillared clays were more active than the samples supported on Al-pillared clays and catalysts supported on alumina. The catalysts were characterized by X-ray diffraction (XRD), thermo-gravimetric analysis, nitrogen adsorption and transmission electron microscopy (TEM). Characterization analysis clearly pointed out to a close interaction of MoS2 with ZrO2 in the pillared clays. Therefore, the highest hydrogenation activities can be related to the presence of an interaction of MoS2 with ZrO2, probably with a different electronic interaction between the active phase and the support, than that reported for the MoS2/Al2O3 System(0 (C) 2004 Elsevier B.V. All rights reserved.