The permeability coefficient model equations of the complex: membrane-concentrations boundary layers for ternary nonelectrolyte solutions are presented. The validity of this model for ternary solutions was verified using a diffusion cell with a horizontally mounted membrane. Concentration profiles obtained on the basis of computer analysis of interferometric pictures were subsequently used for the spatio-temporal structure determination of concentration boundary layers. We report experimental results of the concentration dependence of the concentration boundary layers thickness for steady states. The permeability coefficient of the complex: membrane-concentration boundary layers (Omega(ks)) was calculated on the basis of experimentally determined diffusion permeability of the membrane (omega(ks)), thickness of concentration boundary layers (delta(s)(i)) and solute diffusion coefficient in the solvent (D-ks). It was observed a good agreement between the experimental data of Omega(ks)(i) and ks the results from calculation on the basis of model equation of Omega(ks)(i). (c) 2005 Elsevier B.V. All rights reserved.