Abstract: Two methods for the oxidation of chloromethylated macroporous poly (styrene-divinylbenzene)containing 6% divinylbenzene (CPS)to crosslink-poly (benzoic acid) resins (PBA) have been investigated. By the first method, crosslinked poly(benzyl alcohol) (PBAC) was obtained by hydrolysis of CPS and then oxidized to PBA (1) with dilute nitric acid.By the second method, crosslinked poly (benzaldehyde) (PBAD) was obtained by oxidation of CPS with DMSO and then oxidized to PBA(2)With dilute nitric acid at a lower temperature than that in the oxidation of PBAC with dilute nitric acid.Both PBA(1)and PBA(2) contain no residual chlorine and show an exchange capacity of about 5.5 meq/g(H) or 1.0 meq/ml (Na). However, the product obtained by the second method shows a far lower percentage of cracked beads (<2%) than that by the first method, indicating that PBAD is more readily oxidized with dilute nitric acid at lower temperature than PBAC.The IR spetra of all func-tionalized copolymers mentioned above were investigated. The effects of the concentration of the reagents, the reaction temperatures and time, the solvents added into the reaction mixture were discussed.