We examined the use of polypyrrole/maghemite (PPY/gamma-Fe2O3) and polyaniline/maghemite (PANI/gamma-Fe2O3) magnetic nanocomposites (MNCs) as active agents for removal of heavy metals ions from aqueous media. We have used chemical co-precipitation methods to prepare the maghemite nanoparticles. Subsequently, we synthesized the MNCs through emulsion polymerization of pyrrole or aniline. We estimated the efficiency of these MNCs for Cr (VI) and Cu (II) removal by using batch methods and inductively coupled plasma-optical emission spectroscopy (ICP-OES) to measure the metal content in the solutions before and after use of the MNCs. We evaluated the adsorption capacity (q(e)) of each MNC as a function of the solution pH and of the time allowed for its interaction with the metallic ions in solution. In the Cr (VI) [Cu (II)] case, we determined the value of q(e) as 209 [171] mg/g, for the PPY/gamma-Fe2O3 MNC, and 196 [107] mg/g, for the PANI/gamma-Fe2O3 MNC. In the PPY/gamma-Fe2O3 [PANI/gamma-Fe2O3] MNC case, the time necessary for attaining the q(e) saturation limit was of the order of 15 [35] min for both Cr (VI) and Cu (II). These characteristics compare favorably to those of alternative agents for removal of dissolved metal ions reported in the literature. (C) 2015 Elsevier B.V. All rights reserved.