The nuclear magnetic resonance spectra of packed beds containing the cation exchanger Dowex 50W-X8 in water vary with counter ion. Chemical shifts for water protons internal to the resin bead are in the order H+(lowest frequency) » Zn2+≊ Cd2+≤ Pb2+≊ Mg2+≤ Ag+≤ Ca2+≊ Tl+≊ NEt+4≊ Ba2+≊ Li+≊ NMe4+≊ Sr2+≤ NH4+≤ Rb+≊ K+≊ Na+≊ NBu4+. The concentrated electrolyte model of ion-exchange resins is substantiated by generally good agreement between 1) chemical shifts/g equiv./kg for cations in aqueous solutions referred to NH4+and 2) chemical shifts/g equiv./kg for resin forms referred to NH4+form resin.