The BTX feedstock in a xylene separation unit usually contains trace of unsaturated hydrocarbons. This stream could be treated with active acid clay to remove the unsaturated impurities. Without this treatment the unsaturated hydrocarbons will foul heat exchange equipments and poison catalysts or adsorbents. In this study the BTX feedstock was used to test the adsorption ability of active acid clay. From the kinetic results the adsorption rate constants and decay of adsorption rate constants were derived. These two parameters could be used for estimation of the durability of the active acid operated in the plant.