The separation of liquid binary mixtures in the evaporation-condensation process was investigated in wetted wall column consisting of two concentric tubes. A liquid mixture was evaporated below the boiling temperature, diffuses through an inert gap, and is condensed. Experiments were carried out with isopropanol-water and ethanol-water mixtures in the presence of air, argon or helium as inert gases Experimental results show the significant separation effect even in an azeotropic point. The results of calculation, based on the proposed model described by vapour-liquid equilibrium and Stefan-Maxwell diffusion equations, were found to be in a good agreement with experimental data.