ZSM-5 zeolite membranes were prepared by hydrothermal synthesis. Structural features of the synthesized zeolites were studied by x-ray diffraction (XRD) and scanning electron microscopy (SEM). Adsorptive separation of an n-hexane:thiophene mixture over the obtained zeolites was studied. The effect of the Na2O content in the feedstock for synthesizing the zeolite on the degree of desulfurization was investigated. The maximum amount of thiophene was extracted for zeolite prepared with an Al2O3:Na2O:SiO2:tetrapropylammonium-hydroxide:H2O ratio of 1:30:100:25:10,000. Zeolite modified by NaOH solution of the optimum concentration contained mesopores that could retain sulfur compounds.