Electrochemical and spectroscopic studies demonstrated that the N-truncated amyloid β peptide Aβ5-9 (Arg-His-Asp-Ser-Gly-NH2) possessing histidine at position 2 (His-2) formed ternary complexes with copper(ii) and phosphate anions or phosphate groups of biomolecules. The recognition ability of Cu(ii)-Aβ5-9 toward phosphate species provided a new perspective on designing phosphate-selective molecular receptors.