The separation of hydrogen from gas mixtures may be achieved using perovskite membranes doped with rare earth oxides. The separation flux has been studied in such membranes and is based on a model of the proton transfer mechanism. The thermodynamic equilibrium constants (K-w, K-i, K-ox K-s) and charge carrier mobilities (mu(OH,)mu(Vo), eta(h),mu(c)) for SrCe0.95Yb0.05O3-alpha and SrCe0.95Tm0.05O3-alpha may be estimated by fitting the hydrogen permeation flux model to the actual experimental data for SrCe0.95Yb0.05O3-alpha and SrCe0.95Tm0.05O3-alpha. The results indicate that the thermodynamic equilibrium constants K-H and K-w and the mobility of proton and electrons in SrCe0.95Tm0.05O3-alpha may be higher than for SrCe0.95Yb0.05O3-alpha leading to the higher hydrogen permeation flux in SrCe0.95Tm0.05O3-alpha A parametric sensitivity analysis has been performed by using the New Morris Method to investigate the influence of the thermodynamic equilibrium constants and the charge carrier mobilities on the hydrogen permeation flux model. The results indicate that the hydrogen permeation flux model utilised in this study was most sensitive to the internal electronic equilibrium constant (K-i) value and least sensitive to the hole mobility (Ph). (C) 2007 Elsevier B.V. All rights reserved.