Magnetic mesoporous aluminosilicates (MMAS) were synthesized by hydrothermal method and applied as ultra-deep desulfurization adsorbents for hydrotreated diesel. The size of oleic-coated magnetic Fe3O4 nanoparticles prepared by coprecipitation method was about 20 nm. MMAS shows better desulfurization properties for removal of sulfur compounds than NaY and MCM-41. The amount of Fe3O4 nanoparticles has significant effects on specific surface area/pore volume and acidic properties, thus, can affect the desulfurization properties of MMAS. Desulfurization properties of MMAS can be improved with the increase of temperature from 30-70 degrees C and decrease the oil to adsorbent ratio. With the increase of Fe3O4 content, adsorption capacity first increased and then decreased. The sulfur adsorption of MMAS was due to the synergetic effect of strong molecular affinity of the magnetite to the sulfur compound and large surface area/pore volume of the mesoporous aluminosilicates. (C) 2009 American Institute of Chemical Engineers AIChE 56: 1391-1396, 2010