The utility of FT-Raman spectroscopy in characterizing ion-exchange resins has been demonstrated. Measurements have been made on strong acid-type cation-exchange resin beads of a sulfonated polystyrene-divinyl benzene copolymer. Spectra are compared for the resin with 10 different cations. Classical least-squares fitting is used to quantitate the amounts of different cations in binary mixtures. On-column determinations are demonstrated for displacement of H+ by Na+ and Na+ by Ag+.