1H, 13C and 195Pt NMR spectroscopies are used to identify the products and the binding sites of the complex salts [Pd(dien)(D 2O)](NO 3) 2, [Pt(dien)(D 2O)](NO 3) 2, [Pd(en)(D 2O) 2](NO 3) 2, cis-[(NH 3) 2Pt(D 2O) 2](NO 3) 2, K 2PdCl 4 and K 2PtCl 4 towards the peptides His–Ala and His–Gly–Ala, in aqueous solutions as a function of pD. The 1H, and 13C NMR assignments were made by two-dimensional homo- and heteronuclear experiments for the two ligands His–Ala and His–Gly–Ala. The results show that all Pd(II) salts can substitute protons from all protonation sites of histidine (–NH 2, N3, N1 of imidazole) at very acidic media (pH<1) and form easily –NH 2,N3 chelates. The complex cation [Pd(dien)(D 2O)] 2+ forms N3,N1 imidazole bridges. The Pt(II) salts react with the carboxylate terminal groups of the peptides at pH 3 ( 195Pt NMR range −2000 to −2500 ppm) and form also –NH 2,N3 chelates in weakly alkaline media ( 195Pt NMR range −2200 to −2900 ppm). [Pt(dien)(D 2O)] 2+ does not form bridges but coordinates separately to N1 and N3, with the N3 bound isomer predominating and more so in the case of His–Gly–Ala. K 2PtCl 4 forms 1:2 chelates in alkaline solutions, in contrast to K 2PdCl 4 that forms 1:1 chelates at pH 1. At higher pH values, precipitates are formed.