Abstract: In this study the viewpoint is taken that the supported complexes react with active groups on the surface of support to form new entities which may be called surface complexes. Various interactions between the support and the solution of impregnation have been found, and these interactions may be divided into four classes, (1) those that there is no noticeable chemical interaction between the coordination compound and the support, except the physical adsorption; (2) those that the metal ion of the complex is anchored on the surface through the surface group as a ligand forming a surface complex, or the support provides the central ion for the formation of a surface polynuclear complex through the bridging ligand of the complex; (3) those that the surface of the support provides the central ion for ligands dissociated from the complex or for the solvent molecules; (4) those that the metal hydroxide might be formed, when the acidity of the cation of the support is weaker than that of the metal ion of the complex in aqueous solution.