The new method of computational modeling for multicomponent diffusion with evaluation Of calculation accuracy on the basis of mass balance is suggested. Results of proposed method applied for the modeling of diffusion separation of air species (nitrogen and oxygen) in multicomponent boundary layer on permeable flat plate at helium injection have been presented. Efficiency analysis of proposed method has been carried out and compared to the known calculation method allowing to exclude one of diffusion differential equations. Numerical results of diffusion separation of air species (nitrogen and oxygen) obtained with the controllable calculation accuracy have been presented. (C) 2008 Elsevier Ltd. All rights reserved.