Optimum conditions for removal of Cu(II) ions from both single-component and Cd(II)-containing solutions by ligand-modified micellar-enhanced ultrafiltration (LM-MEUF) in the presence of cetyltrimethylammonium bromide (CTAB) and triton X-100 (TX100) micelles were determined. TX100 was not found to be effective in Cu(II) separation by LM-MEUF. The most effective ligand in CTAB micellar media, out of 20 ligands, was found to be 2,4,6-tri(2-pyridyl)-1,3,5-triazine (TPTZ) in removal of Cu(II) ions from single-component solutions. 99.99% removal of 5.0 x 10(-4) mol L-1 Cu(II) ions from single-component solutions could be provided in the presence of 5.0 x 10(-3) mol L-1 CTAB and 1.0 x 10(-3) mol L-1 TPTZ. Complete removal of 5.0 x 10(-4) mol L-1 Cu(II) ions from 5.0 x 10(-4) mol L-1 Cd(II)-containing solutions could be achieved by LM-MEUF with 6.4% Cd(II) rejection in the presence of 1.3 x 10(-2) mol L-1 CTAB and 2-hydroxy-1-(2-hydroxy-4-sulfo-1-naphthylazo)-naphthalene-3-carboxylic acid. The results demonstrated that metallic ions of quite similar properties can be separated simply by a membrane filtration process and that Cu(II) removal can be provided not only by anionic but also by cationic micelles. The results of this study were discussed in a comparative way with those obtained in a LM-MEUF process performed previously in the presence of sodium dodecyl sulfate (SDS) micelles. The ligands were shown to exert similar effects in the presence of both cationic CTAB and anionic SDS micelles, and a mechanism was proposed for Cu(II) removal by LM-MEUF.