A new composite material able to remove hexavalent chromium Cr(VI) ions from aqueous solutions was performed by in-situ oxidative polymerization of 1,8-diaminonaphthalene (1,8-DAN) on the bentonite surface from Binh Thuan province, Vietnam. The bentonite/poly(I,8-diaminonaphthalene) composite had high adsorption capacity of Cr(VI) at pH 2. To evaluate the adsorption capacity, the effect of contact time, initial concentration on the adsorption were also investigated. Equilibrium data of Cr(VI) onto this composite adsorbent was well described by Langmuir isotherm model which indicated a physical adsorption process.