, Bulk Fe-V mixed sulfide catalysts prepared by the co-precipitation method were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fe-57 Mossbauer spectroscopy. Hydrodeporphyrinization (HDP) of vanadyl octaetil porphyrine (VOOEP) was used as a catalytic test. XRD and Mossbauer analysis showed the existence of two structural phases based on NiAs sub-cell, i.e. monoclinic (Fe, V)(3)S-4 and hexagonal (Fe, V) (1-x),S. TEM micrographs reveal similar morphology (particle size and shape) for all the catalysts except for pure iron sulfide, which presented larger particle size. Mossbauer spectra of fresh and used catalysts indicate that phases are rather stable at reaction conditions. A correlation between specific HDP activity and the amount of monoclinic (Fe, V)(3)S-4 phase is evidenced. (c) 2005 Elsevier B.V. All rights reserved.