A carboxylic gel-type resin, poly-4-vinylpyridine-methacrylic acid-N, N'-methylenebisacrylamide is designed and synthesized in order to be able to incorporate both FeIII and, potentially, also AuIII in its polymer framework. Along with the gradual substitution of H+ with Na+, of Na+ with Fe3+/3 and after a very controlled and gradual precipitation of FeIII as oxihydroxides induced by the hydrolysis of urea directly inside the nanoporous domains of the metalated resin particles, an organic-inorganic composite is obtained. The material is characterized with TGA, ESEM, XRMA and Mössbauer spectroscopy. [ABSTRACT FROM AUTHOR]