This article focuses on the experimental work supported by theoretical model of the multicomponent mass transfer during extraction driven by spontaneous interfacial convection (SIC). The regularities of individual and joint unidirectional and reciprocal mass transfer of components with different surface-active properties in the benzene-water extraction system at a flat phase interface are considered. The article demonstrates that both the diffusion and convective hydrodynamics of the flow affect the intensity of unidirectional and counter-mass transfer of the components under the conditions of SIC. Marangoni instability at the interface causes local convection, which enhances the mass transfer rate considerably. Experimental studies have shown that the joint unidirectional mass transfer of acetic acid and iodine from organic phase to aqueous phase under the conditions of SIC can be characterised by an increase in the iodine mass transfer coefficient in comparison with its individual mass transfer. It has found that with the acetic acid the unidirectional mass transfer of iodine can be increased by more than 20 times compared to its mass transfer without acid. However in case of counter-transfer of acetic acid and iodine, both the acetic acid as well as iodine mass transfer coefficients decrease compared to their individual mass transfer situations. The experimental data are in accord with the theoretical justification. A simplistic semi empirical theoretical model is developed for joint mass transfer, to estimate the coefficient of mass transfer of the components. The satisfactory convergence of the experimental and calculated data are shown. (C) 2018 Elsevier Ltd. All rights reserved.