In this study, layered double hydroxide (LDH) consisting of Mg-II and Fe-III (Mg/Fe-LDH) was synthesized by using a combination of coprecipitation with hydrothermal aging, and its anion-exchange properties were investigated. Through various analyses, the chemical formula of the proposed Mg/Fe-LDH was determined to be [Mg0.76Fe0.24(OH)(2)](Cl-)(0.21)(CO32-)(0.02)center dot 0.76H(2)O. Furthermore, amorphous Fe-III impurities were contained in the present Mg/Fe-LOH. The proposed Mg/Fe-LDH exhibited clear selectivity for nitrate ions dissolved in water. This selectivity for nitrate ions can be explained by an anion-sieve effect by the existence of amorphous Fe-III impurities. Our findings suggest that it is possible to synthesize LDHs with high selectivity for various anions by effective hybridizing Fe-III impurities. (C) 2012 Elsevier B.V. All rights reserved.