Amorphous zirconium phosphate Zr-3(PO4)(4) (referred to as ZrP) with a specific surface area of 114 m(2) g(-1) was prepared by a sol-gel method. Its acid properties were studied by: 1. butan-2-ol conversion 2. LR spectroscopy of adsorbed pyridine and 3. microcalorimetric measurements of heat of ammonia adsorption, It was found that the sample exhibits two kinds of acidic Bronsted sites and also Lewis acidity. The strongest acid sites retained pyridine until 623 K. True Lewis acidity was associated with zirconium atoms emerging on the surface of the sample. Sulfided samples of Mo/ZrP and NiMo/ZrP were tested in biphenyl hydrogenation, thiophene hydrodesulfurization and pyridine hydrodenitrogenation. Their intrinsic activities were significantly higher than an industrial NiMo/Al2O3 catalyst. Catalyst characterization by conventional spectroscopic techniques did not show any crucial difference between NiMo/ Al2O3 and NiMo/ZrP, However, on the sulfided samples, electron microscopy observations revealed that the MoS2 crystallites are very well dispersed on the support and smaller on ZrP than on alumina. In addition, the stacking of MoS2 layers was found to be equal to 1.6 when using ZrP instead of 2 on Al2O3 All these features were correlated to the catalytic performances of the samples and to ZrP surface properties that are believed to contribute to the stabilization of highly dispersed MoS2 species.