Thiosulfate-intercalated zinc-aluminum LDH was prepared by anion exchange reaction. The interlayer thiosulfate ions of this LDH could be quantitatively oxidized to tetrathionate ions using iodine and sulfate ions using H2O2. Both of these intracrystalline reactions are topotactic in nature. The reaction of the LDH with molecular iodine makes it a potential material for the removal of radioactive iodine from effluents.