Anion exchanged hydrotalcites have been characterized by means of X-ray, thermal and infrared spectroscopic methods. The sample has been treated in the solution containing various anions such as S^2-, SO₄^2-, SO₃^2-, HSO₃^-, S₂O₃^2-, S₂O₄^2-, S₂O₅^2-, SCN^-. The dehydration temperature of structural OH as well as the CO₃ remarkably shifts from 400 to 480°C in the samples exchanged with anions such as SO₄^2-, HSO₃^2-, S₂O₅^2-, which suggests the presence of some interactions between the anions and the structural OH. All the sulfur atoms exchanged are retained in the temperature up to 980°C. Infrared spectroscopic and thermogravimetric data show that the exchanged SO₄ occupy the site of CO₃.