Hydrotalcites (HTx) of different Mg/Al ratio (x was Mg/Al ratio; 2,3,4) were synthesized by co-precipitation method. Calcined hydrotalcites (CHTx) at 500 degrees C have been shown to recover their original layered structure by adsorbing nitrate or nitrite from aqueous solution. The adsorption kinetics study showed that the Pseudo-second-order kinetic model could be used to describe both nitrate and nitrite removal satisfactorily. The equilibrium isotherm showed that the Langmuir model gave a better fit to the experimental data than the Freundlich model. As the Mg/Al ratio increases from 2 to 4; the electric charge density between the layers becomes weaker; the interlayer spacing increases and the sample shows greater adsorption capacity. The CHT4 exhibits maximum adsorptive capacity, and the maximum adsorption capacity obtained by Langmuir model for nitrate adsorption was 34.36 mg N/g while for nitrite was 37.17 mg N/g. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FTIR). (c) 2012 Elsevier B.V. All rights reserved.