A method for the determination of tannin in tea samples is described. The technique is based on the oxidation of tannins with an excess of cerium(IV) sulphate and subsequent determination of the excess by back-titration with ammonium iron(II) sulphate solution. Although this method and the Löwenthal procedure appear to determine the same tannins, the precision of the former is ± 1·24 per cent., while that of the latter is only ± 10·12 per cent.