Individual metal recovery and separation by solvent extraction has been an important technique in pollution control as well as in hydrometallurgical processes. Synergistic extraction and separation of two cations, e.g., Cu(II) and Zn(II), a cation and an anion, e.g., Cu(II) and Cr(VI), and two cations and one anion, such as Cu(II), Zn(II), and Cr(VI), have been demonstrated employing a novel hydrophobic microporous hollow fiber membrane-based (HFM) extraction technique. The extraction selectivity of Cu(II) and Zn(II) by LM 84 (anti-2-hydroxy-5-nonylacetophenone oxime) and bis(2-ethylhexyl)phosphoric acid (D2EHPA), respectively, in a two-fiber-set HFM extractor is significantly enhanced due to competitive extraction. The efficiencies of extraction of Cu(II) and Cr(VI) by LIX 84 and tri-n-octylamine (TOA), respectively, are increased due to the self-control of the aqueous feed pH. A simplified mathematical model for synergistic extraction of Cu(II) and Zn(II) has been developed. The model predicts the observed extraction and separation performance well. In the novel HFM extractor, the extraction rates of Zn(II) and Cu(II) by D2EHPA and LM 84, respectively, were controlled by the aqueous and organic boundary layer resistances as well as the interfacial reaction resistances.