The estimation of hydrogen permeation mole flux was performed by previously introduced theoretical equation which considers the decrease in H-2 concentration at the membrane surface, and was compared with experimental result, for various hydrogen mixtures with different inlet H-2 mole fractions and species. A flat sheet 77 wt.% Pd/23 wt.% Ag purification membrane with effective surface area of 3.14 x 10(-4) m(2) was used. For H-2:N-2 mixture, the comparison was performed under various feed flow rates (2.78 x 10(-5)-2.50 x 10(-4) mol/s), for inlet H-2 mole fraction of 0.70-0.80, at reference membrane temperature of 623 K and total upstream pressure of 0.25 MPa. Then, nitrogen was subsequently replaced with argon (Ar), helium (He) and carbon dioxide (CO2) to investigate the applicability of the estimation method for various H-2 mixtures with different species. The results demonstrate that the effect of H-2 permeation itself plays a significant role for permeation with H-2 mixture, which induces the phenomenon of concentration polarization. Overall, the introduced method is able to estimate H-2 permeation mole flux for H2 mixture, both qualitatively and quantitatively, regardless of inlet H-2 mole fraction and species. (C) 2015 Elsevier B.V. All rights reserved.