Abstract: Valinomycin is one of the most "important" antibiotic-ionophore. It is known to form more or less stable equimolar complexes with alkali ion in neutral solvents^[1] Some synthetic carriers showing similar properties have also become known, among them, the most frequently seen are compounds like depsipeptides, cyclic polyethers and polythioethers^[2]. These compounds are able to complex with alkali and alkaline-earth ions and make them soluble in nonpolar media. Such quality has attracted great research interest. In this note, we report our recent investigation on the migration of alkali and alkaline-earth metal ions across an organic phase as influence by cyclopeptides cyclo-(Pro-Gly)_3,4 synthesized in this laboratory.