A series of Mo (W) catalysts promoted by Ni and supported on pure siliceous SBA-15 was prepared using Keggin-type heteropolyacids (H3PMo12O40 or H3PW12=O-40) as active phase precursors. These catalysts were compared with corresponding NiMo(W)/SBA-15 catalysts prepared from the traditional precursors (ammonium heptamolybdate, ammonium metatungstate). Prepared catalysts were characterized by N-2 physisorption, small- and wide-angle XRD. UV-vis DRS, FT-IR, TPR, P-31 MAS NMR, HRTEM and evaluated in hydrodesulfurization of 4,6-dimethyldibenzothiophene (4.6-DMDBT). It was found that both Mo and W catalysts prepared from heteropolyacids showed better performance in deep HDS of 4.6-DMDBT than the counterparts prepared from traditionally used Mo (W) ammonium salts. The possible reasons of this phenomenon are discussed. (C) 2008 Elsevier B.V. All rights reserved.