The increased pollution of surface water and groundwater by nitrate and ammonium ions, make it necessary to find acceptable environmental solutions for removal of these materials from water resources. The adsorption method is the most usual way for the removal of water pollution by using porous adsorbents like activated carbon, silicon dioxide, activated aluminum, and clay minerals like: zeolite, bentonite, vermiculite, sepiolite and palygorskite. Clay minerals are useful adsorbents for removal of water pollution because of their large specific surfaces, porous surfaces, high cation exchange capacity and low expense in the other hand. The surface specifications of clays could be changed by using organic surfactants, that are capable of adsorbing onions and nonpolar organic materials. If foursquare surfactants exchange with cations of external surface of clay, its external surface will change and it will have positive charges. In this study, the surfactant modified bentonite (SMB), was used for removal of nitrate onions from aqueous solutions. Techniques such as XRD, FTIR, SEM and EDX were used to characterize the adsorbent attribute of the bentonite and its ability as an adsorbent, while variable initial concentration of nitrate, the amount of adsorbent, contact time, temperature and pollutant's solution pH were investigated. In batch experiments, the optimum pH of nitrate solution was found to be 5.5, equiblirium time 120 minutes and optimum amount of adsorbent 0.5 g. With increasing initial concentration of nitrate from 5 to 300 mg/L, the nitrate adsorption efficiency decreased from 92.5 to 47.5% and with increasing the temperature from 20 to 60 adsorption efficiency increased from 88.47 to 93.5%. Isotherm models, Langmuir, Freundlich, Langmuir-Freundlich and Redlich-Peterson were fitted to nitrate adsorption equiblirium data. Among these models, the Langmuir model showed the best fit to nitrate adsorption data and maximum anticipated adsorption from Longmuir model was found to be 10.15 mg/g. Kinetic models, pseudo first order, pseudo second order, intra particle diffusion and power function were used to describe kinetic data of nitrate adsorption. Pseudo second order model, had the best fit to nitrate adsorption data with modified bentonite indicating that chemical adsorption is the main controlling mechanism. To complete the studies on the introduced adsorbent, column adsorption experiments were performed to check the absorbent performance during continuously injected nitrate solution into the adsorbent column, until the adsorbent has been saturated. The results for columns with continuous inflow indicated that the maximum capacity of adsorption of nitrate ions, for adsorbent column with diameter of 1cm, 2cm modified bentonite, 13 cm sand and input concentration of 15 mg/L and input rate of 0.5 ml/min, was 3.45 mg/g and for adsorbent column with diameter of 2 cm, 2 cm modified bentonite and input concentration of 100 mg/L and input rate of 1 ml/min, was 15.26 mg/g. Column experimental results show, with increasing the initial concentration of nitrate solution, the capacity of adsorption increased, but all the adsorption places were filled quickly, so saturation time of the adsorbent reduced. The results of this experiment showed that modified bentonite with cationic surfactant HDTMA-Br, has high capability for removal nitrate from equeous solutions. Keywords : Nitrate, Bentonite, Surfactant modified bentonite, Adsorption, Batch experiment, Column experiment