Zn,Al-hydrotalcites interlayered with hexacyanoferrate(II) and hexacyanoferrate(III) ions have been synthesized by different methods. These include rehydration of the product obtained by calcination of the carbonate form at 500 degrees C, anionic exchange of nitrate- and terephtalate-containing hydrotalcites, and direct synthesis. Both hexacyanoferrate(II) and (III) species are present in the interlayer space, but in different ratios, suggesting that a redox process takes place in this interlayer.