Hydrogenous atactic polystyrene lonomers (SPS) with sodium cation was analyses by fourier transform infrared spectroscopy. These show that the formation of a strong ionic field with the sulfonate ions which participate in cluster formation. It has also been found that the spectra are sensitive to a modification by sulfonation of adjacent functional groups. These results also clearly show that the vibrational bands depend on the strength of the bonds and charge of the cation. The analysis also confirmed the sulfonate group in the para-position on the benzene ring of the styrene unit.