Transport selectivity and kinetics of amino acids through di(2-ethylhexyl) phosphoric acid-kerosene bulk liquid membrane have been studied. The liquid-membrane system exhibited excellent transport selectivity for amino acids containing a side chain of high lipophilicity constant, like L-phenylalanine, L-tryptophan, L-leucine, and L-isoleucine. Main factors affecting the amino acids transport have been discussed. As a target amino acid with bulky aromatic side-chain of L-phenylalanine, the influence of its concentration and the concentration of di(2-ethylhexyl) phosphoric acid on the interfacial tension, and the effect of temperature on its transport through the bulk liquid membrane were investigated. The transport kinetics of L-phenylalanine could be analyzed in the formalism of a reversible pseudo-first-order reaction followed by an irreversible pseudo-first-order reaction. The pseudo-first-order apparent rate constants of the interfacial transport of L-phenylatanine for the extraction reaction, extraction back reaction, and stripping reaction were estimated. (C) 2004 Elsevier B.V. All rights reserved.