Chromate sorption on pyridine strong base anion exchangers with different functional groups (methyl, ethyl, and butyl groups), at the quaternary nitrogen atoms, was studied as a function of various initial concentrations (100-1500 mg Cr/L) and counterion type. The studied resins in the Cl-1 form have higher Cr(VI)-retention capacities than those in the SO2-4 form. The pyridine strong base anion exchangers showed a selectivity reversal for the sulfate and chromate anions compared to that of the commercial resins. The alkyl substituent length of the quaternary nitrogen atoms exerted a substantial influence on the Cr (VI) -retention capacity values for the resins in the Cl- form; the chromate anions preferred resins with methyl functional groups, that is, resins with a greater hydrophilic structure. For the resins in the SO2-4 form the length of the substituent at the quaternary nitrogen atom had only a negligible influence on their Cr(VI)-retention values. (C) 2004 Wiley Periodicals, Inc.