Poly(allylamine)-metal complexes with different metal ions (Co(II), Cu(II), and Ni(II) in conjunction with an ultrafiltration membrane were prepared. They were obtained varying the polymer/metal ion ratio and the pH (1, 3, 5, 7). The retention at pH 1 and 3 was lower than 10%. The study was carried out with the polymer-metal complexes obtained at pH 5 due to the high retention but not at pH 7 because Cu(II) precipitated. They were characterized by FT-IR, UV-Vis spectroscopy, thermogravimetric analysis, and intrinsic viscosity