The extraction of Ni(II) by dialysis through a porous polysulfone membrane is enhanced by using an hydrosoluble polycarboxylate polymer diluted in the receipt compartment. The flux of Ni(II) depends on both the Ni(II) and the polymer concentrations. In an acidic solution, the extraction rate also depends on the pH of the receipt phase which contains the chelating polymer. Due to the absence of water-solvent interface, the overall mass transfer coefficients of Ni(II) are more important than for water-solvent liquid extraction systems.