Magnetite-mesoporous silica composites were synthesized as a new adsorbent for desulfurization from natural gas. When nano-sized magnetite was added to the reactant solution prior to a sol-gel reaction, mesoporous silica was formed surrounding nano-sized magnetite, and the silica domain size was reduced significantly comparing with the case that no magnetite was added. This composite shows high capacity for adsorption of methylmercaptane in the presence of methane while mesoporous silica or magnetite only had little adsorption capacity. The sulfur adsorption of this composite show 20 times higher capacity than the mesoporous silica 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 silica.