Residual sulfides modeled by 0.002-0.01M Na2S in pure H2O or in aq. 0.001-1.0M NaOH, were oxidized to sulfates, (a) batchwise or (b) in a column, with styrene-DVB (P) copolymers modified to yield [P]-SO2NXNa (X = Cl, Br) and [P]-SO2NCl2. The column-leaving effluents contained less than 10 ng S2-/L In mode b, the solution was passed, 0.3-0.6 L/h (6-12 bed vols./h), through a 50-mL (50-cm high) bed With X used in overstoichiometric quantities, the excess X remained unaffected in the resin. The Cl and the Br copolymers were most effective in neutral or weakly alkaline (pH = 5) and in fairly alkaline (pH > 5) solutions, resp., otherwise SO42- + S were formed The Cl-2 copolymer required weakly acid conditions; in strongly alkaline, it was converted into the Cl-form.