Separation experiments of nickel and cobalt are carried out by a porous glass packed column using terdentate diethylenetriamine and quadridentate triaminotriethylamine as eluent at 298 It. The influence of dentate number of amine on separation efficiency of metals is investigated referring to the results of separation experiments for unidentate ammonia and bidentate ethylenediamine reported before. Increasing dentate number of amine decreases the amount of metal adsorbed, promotes the elution of metal and enables us to separate nickel and cobalt at lower concentration of amine, and to completely recover cobalt The optimum value of pH for separation is 8 for uni to terdentate amines and 6 to 7 for quadridentate amine. These results show that the elutions of metals are under the control of two kinds of the factors, uni., adsorption of metal by amine complex ion and desorption of metal by free amine.