In the framework of research on desulfurization by adsorption, an experimental study of the adsorption selectivity between thiophene and toluene molecules in liquid n-heptane solutions onto NaY (Si/Al = 2.4) and NaX (Si/Al = 1.2) zeolites has been carried out. It investigates the possibility for these commercially available adsorbents to be used in a desulfurization process operated under ambient conditions without using H-2. Dynamic adsorption experiments were performed at room temperature mainly at two concentration ranges: 25 mmol, L-1 for competitive adsorptions and 1.25 mmol, L-1 for single-solute experiments. Adsorption isotherms of thiophene and toluene on NaY and NaX sorbents have been obtained. On the NaY zeolite, toluene is favorably adsorbed (alpha(thio/tol) = 0.60) while an inverse behavior is observed with NaX sorbent (alpha(thio/tol) = 1.63). This exhibits many differences in sorbate/sorbent interactions with slight changes in the adsorbent nature. Besides, the selectivity on NaY sorbents has been found to depend significantly on the concentration range. Such a phenomenon agrees with the fact that the sorbates' adsorption over NaY zeolites cannot be described by a simple Langmuir model. Thiophene adsorption onto NaY undergoes a peculiar phenomenon, since its isotherm exhibits an inflection at a coverage of 1 molecule per alpha-cage.