Neutron diffraction measurements on (CI)-C-35/(CI)-C-37 isotopically substituted anion exchange resins were carried out in order to obtain direct information on the local structure around the chloride ion absorbed in the resin. Structural parameters concerning the first nearest-neighbor interaction of chloride ions were determined through a least-squares fitting procedure of the observed first-order difference function, Delta(Cl)(Q). It has been revealed that the chloride ion is neighboring an ion exchange group (-CH2(CH3)(3)N+) with a Cl-center dot center dot center dot N distance of 3.10(3) A, and simultaneously bonded with 2.4(1) D2O molecules with a Cl-center dot center dot center dot D distance of 2.25(2) angstrom. The second and third nearest water molecules around Cl- have also been observed. These results indicate that the direct ionic interaction between Cl- and -CH2(CH3)(3)N+ drastically reduces the number of first-neighbor water molecules around Cl- but enhances the long-distance structuring of the remaining water molecules in the environment surrounded by a hydrophobic polymer matrix.