NiMo supported on Al- and Ti-PILCs catalysts were prepared and tested in the hydrotreating of residual atmospheric gasoil (375 degrees C cut), from Maya type crude (3.7 wt.-% sulfur, 11 wt.-% asphaltenes, 21.5 wt.-% aromatics, 16 wt.-% polars). At 400 degrees C NiMo/Ti-PILC lowers the asphaltene fraction by 77.2 wt.-%, while aromatics decrease by 53.5 wt.-% and polar fractions diminishes by 43.8 wt.-%. This is about 4.5, 9.3 and 22.5 wt.-% higher than NiMo/Al2O3 reference catalysts. The relative HDS rates for NiMo/Ti-PILC are 40.4, 22.8 and 18% HDS/m(2) for sulfur removal in the asphaltene,polar and aromatics fractions, respectively. In the same sequence NiMo/Al2O3 catalysts give 11.4, 1.6 and 19.6% HDS/m(2). The X-ray microanalysis of clay-supported catalysts, in a single plate mode, after reaction and regeneration, indicates significant variations in the metal and sulfur content on the flakes faces with respect to the edges, which may correlate with catalytic active sites for HDS. After regeneration by means of THF solvents, refluxing and calcination in air at 380 C, both the physical and catalytic properties of NiMo/Ti-PILC and NiMo/Al2O3 were recovered. The active metal redistribution of Ni on clay flake edges seemed responsible for enhancing the activity after regeneration.