A new layer evaporation model for multi-component real liquid mixtures, based on activity coefficient calculation on quantum chemical basis is presented. The proposed method applies the COSMO-RS theory for the estimation of vapour-liquid equilibrium of non-ideal solutions and the Maxwell-Stefan diffusion and convection theory for the calculation of gas phase transport characteristics of the components. Computational fluid dynamics (CFD) simulation by COMSOL Multiphysics and salvation mixture thermodynamics by COSMOtherm program packages have been used to perform the calculations for the quasi-equilibrium evaporation of compounds from liquid surface. The activity coefficients, the liquid and vapour phase compositions, the cumulative and components evaporation fluxes have been computed. The good predictive ability of the resulting simulation model was tested on experimental evaporation data of 2-5 components mixtures. (C) 2011 Elsevier Ltd. All rights reserved.