Persimmon tannin was immobilised with formaldehyde (the aldehyde gel) and potassium peroxodisulfate (the persulfate gel). The resulting gels have high abilities to adsorb iron. The persulfate gel can adsorb iron from both iron(II) and iron(III) solutions with high efficiency. The adsorption of iron(III) by the persulfate gel was rapid and was affected by the solution pH, the concentration of iron in solution, and the mass of adsorbent. Adsorbed iron was easily desorbed with 0.1 mol dm(-3) HCL solution. The gel can be repeatedly re-used for iron recovery using the adsorption-desorption cycle. The persulfate gel could remove trace amounts of iron in a sake-brewing water to facilitate the production of high quality sake.