Highly swollen ion-exchange resins result from the polymerization of diallylamine in the presence of 2 mol% of a bis-diallyl-amino compound as the cross-linking reagent. It is shown that post cross-linking with a dihalo compound is an acceptable method for decreasing the swelling propensity of the resins. The secondary amino groups are then converted to tertiary types, although there is some formation of quaternary ammonium groups which is detrimental in ion-exchange resins which are to be regenerated thermally. The aromatic compound α,α-dichloro-p-xylene is more suitable than the less rapidly reacting aliphatic compound Br(CH2)4Br and the even slower reacting reagent Cl(CH2)4Cl. However, satisfactory products are obtained with the use of Br(CH2)6Br. The additional cross-linking of the poly-diallylamine results in a lowering of the basicity level by one to two orders of magnitude, with the electron-withdrawing aromatic product exhibiting the greatest effect. Better pH buffering properties are usually obtained when the product is subsequently treated with hot alkali, which transforms any quaternary ammonium groups present to tertiary amino types.