The objective of this work is the evaluation of the separation/concentration of L-phenylalanine by means of nondispersive extraction and backextraction in hol; low fiber modules and the determination of the equilibrium and kinetic parameters, which will allow the description of the separation process. An organic solution based on Aliquat 336, 30% (v/v); isodecanol, 30% (v/v); and kerosene is used as a selective extraction medium. The extraction of L-phenylalanine takes place at pH 10.5, and the backextraction takes place at pH 0.5, with a sulfuric acid solution. The nondispersive extraction and backextraction process for the separation/concentration of L-phenylalanine is described by means of a mathematical model based on seven differential equations. Its resolution is performed by the gPROMS simulation package after introduction of the chemical equilibrium extraction parameters K-qE = 1.32 and K-1 = 1.25 x 10(-3), allowing calculation of the optimum value of the mass transfer coefficient, K-M = 1.12 x 10(-8) mis, which is in the range of previously reported values. This model and its parameters are useful for establishing the viability of the industrial separation/concentration processes of L-phenylalanine.