The periodic structure of layered hydrotalcite (HT) with Mg/Al 2: 1 ratio is optimized with various intercalated anions, namely mono-and di-hydrated chloride, nitrate, carbonate, iodide and triiodide. The geometrical parameters are in good agreement with the available experimental data, so that the triiodide structure, not yet characterized experimentally, provides a reliable estimate of the expected interlayer distance. The change of the triiodide formation energy and iodide/triiodide redox potential upon intercalation in HT are also estimated, to evaluate the possible use of this environment as contact electrolyte in dye-sensitized solar cells. (C) 2010 Elsevier B.V. All rights reserved.