Combined processes consisting of chemical reaction and mass transfer are widely used in modern chemical engineering practice. These processes are mostly of a multicomponent nature which generate a need for matrix theoretical description. The governing differential equations are coupled through both diffusional and chemical interactions of components. In a similar way, the appropriate boundary conditions at the interface are coupled because of conjugation of the contacting multicomponent fluid phases. In this paper a calculation method combining analytical and numerical technique is presented for solving various mathematical models of this sort. The method makes it possible to determine local concentrations of components and temperature in multicomponent systems and, based on these data, to obtain all the relevant information about the process considered. Various flow and physico-chemical conditions are treated, mathematical models, calculation methods and relevant computer programs are developed and examples of process design are demonstrated.