Three lightly sulfonated polystyrenes containing 6.1 mol % sulfonate groups neutralized with Ni2+, Cd2+, and Zn2+ were studied with the extended X-ray absorption fine-structure (EXAFS) technique. Using the simulation package FEFF5, it was found that the atomic arrangement which led to the best description of the experimental data was very similar for the nickel- and zinc-neutralized materials. Nickel was octahedrally coordinated to oxygen in the first shell, while zinc was tetrahedrally coordinated to oxygen. In both cases, the second shell was sulfur atoms with a metal-oxygen-sulfur angle of 135-140 degrees. In octahedrally coordinated nickel, nearest-neighbor metal atoms are located along one "magic angle" line and close to, if not on, an orthogonal axis, while for tetrahedrally coordinated zinc, zinc atoms are contained on-a Single line. Because of the finite domain size, the metal atoms at the boundary between the ionic aggregates and the polymer matrix are probably coordinated to oxygen from water. Based on the experimental error, it is possible that nickel may have two waters of hydration in the immediate coordination structure, although the fit is not as accurate as in the former case. In the cadmium-neutralized material, cadmium cations are also octahedrally coordinated to oxygen. However, simulations of 6-fold sulfonate structure are definitely inferior to those with two oxygen atoms belonging to water molecules and the remaining four oxygens from sulfonate groups. Overall, the structures are well-ordered, and some implications of these results are discussed.