Cation exchange equilibrium distribution coefficients (A) with Amberlite IR-120 have been determined for 20 metal ions in media consisting of mixtures of 0.1MHNO3and varying concentrations, viz., 0.01, 0.05, 0.25, and 1.2M, of ammonium acetate. The metal concentrations were so chosen that the ratio of total amount of cation to total resin capacity ≈ 0.4, sufficient to ensure exchange. The values of separation factors of various metal ion pairs have also been evaluated, and separation possibilities for ions in a number of binary and ternary mixtures have been proposed.