The generation of metal nanostructures by radiation-induced reduction of copper ions in aqueous dispersions of macromolecular complexes of poly(acrylic acid) and polyvinylimidazole has been studied in the pH range of 2.3-4.3. It was shown that an effective coordination number of Cu2+ in the complex with polymer units decreased at lower pH, which resulted in dramatic increase of the nanoparticle formation rate. As demonstrated by transmission electron microscopy, using the poly(acrylic acid)-polyvinylimidazole-Cu2+ complexes as precursors allows one to control the nanoparticle size and promotes assembling of spatially ordered supramolecular structures. As revealed by dynamic light scattering, decreasing the medium pH leads to ripening of the poly(acrylic acid)-polyvinylimidazole-Cu2+ particles. The obtained results provide an evidence for strong effect of the pH value on the spatial organization of nanoparticles in irradiated suspensions. In the case of less acidic medium (at pH 3), assembling of nanoparticles occurs in flabby interpolymer particles, whereas at lower pH the metal nanoparticles are produced in the templates of the perfect macromolecular nanostructures.