Binding of palladium (II) ion by gelatin was studied by measuring the absorption spectrum of PdCl₄^-2 (λ_max=280 nm) in the presence of gelation. Carboxyl or amino groups were blocked chemically by methylation or acetylation, respectively, and methionine residue was oxidized by hydrogen peroxide. The effects of modified gelatin, several amino acids and related substances on the absorption spectrum of PdCl₄^-2 suggest the role of the functional groups of gelatin to react with palladium (II) ions. The formation of some species of palladium (II) gelatinates was suggested from equilibrium dialysis. pH titration of the mixture containing potassium tetrachloropalladate (II) and gelatin showed that palladium (II) ion was firmly bound by gelatin below pH 6.0. It was concluded that palladium (II) ion formed a chelate or a simple gelatinate with any of histidine, lysine, methionine, glutamic acid and aspartic acid residues.