Methods are described for the fractionation of the complex mixture of phenolic substances and their oxidation products occurring in manufactured tea. Products of oxidation detected include two fractions, S I and S II, responsible for the greater part of the colour intensity of a tea infusion, and nine unidentified substances, A, B, C, D, P, Q, X, Y and Z. S I and S II have been obtained almost free from other contaminants. They have acidic properties, and mean molecular weights of the order 600. They are probably mixtures of dimers, each dimer consisting of two oxidized flavanol units. X and Y have no acidic properties and are also distinguished from S I and S II by several characteristic colour reactions. P may be an anthocyanidin.