Department of Chemistry, North Bengal University, Dist. Darjeeling Manuscript received 12 March 1971; revised 28 February 1973; accepted 23 April 1973 Cation exchange studies of [Coen3]3+ have been carried out from Na-Coen3-Amberlite IRC-50 resin against different ions. The order of release of [Coen3[3+ from the resin matrix is in the sequence : Cs < Rb < K < Na < Li < NH4 < Mg < Ca. The quaternary anunonium ions, such as (CH3)4 N, (C2H5)4N, CTA (cetyltri-methylarnmonium) and CP (cetyl pyridinium) fail completely to exchange [Coen3]3± from its resin complex. The plots of log (selectivity co-efficient) vs. hydrated ionic radii as well as reciprocal of the Debye Huckel parameter a° give linear graphs suggesting that both the parameters may be found to correlate with the relative affinities of the ions for the resin surface.