The method to assess the relative importance of the individual mass transport resistances has been developed for multicomponent systems where each of the constituent resistance is defined by an appropriate matrix of mass transfer coefficients. This method is validated using multicomponent membrane extraction as a test case. The process is both energy-efficient and easy to operate. The process was studied experimentally as a test case. The effect of all the individual mass transport mechanisms on the overall mass fluxes is studied. If resistances to mass transfer, identified by the method as insignificant, are omitted from the simulations, the agreement between numerical predictions and the experiment is not impaired. It is also demonstrated that the accuracy of calculating mass fluxes in membrane extractors became worse when the variation of diffusivities with concentration along the diffusion path is neglected, and also, when the effect of the membrane on interrelationships between the mass fluxes (referred to the stationary system of co-ordinates) is not taken into account.