The effects of heat treatment in air on H-2 sorption over the free-standing 25-mu m cold-worked Pd-Ag25 wt% and Pd-Au10 wt% membrane surfaces were investigated. The equilibrium sorption results demonstrated that H-2 solubility did not change for both Pd-Ag and Pd-Au membranes before and after air oxidation at 300 degrees C. The sorption kinetics data revealed a much faster H-2 sorption rates for the as-received Pd-Au membrane than the as-received Pd-Ag alloy. The heat treatment in air accelerated the H-2 sorption kinetics for both membranes at small H-2 equilibrium pressure (EP) of 0.16 kPa. However, the oxidation enhancement extent is greater for Pd-Ag and the disparity becomes more significant when EP increases. The sorption rate enhancement for Pd-Ag membrane existed over a wide range of EPs even though the enhancement effect decreased with increasing EPs. For Pd-Au membrane, the enhancement induced by air oxidation decreased sharply when EP increased because the sorption rate is already very fast for the as-received Pd-Au alloy and there is less latitude for further improvement than Pd-Ag membrane. It is found that the variation of H-2 sorption rates over membrane surfaces correlates to the change of H-2 permeability. After heat treatment in air, the Pd-Ag membrane experienced a systematic increase in H-2 permeability with higher permeability increase at lower pressures while there was basically no permeation increase due to air oxidation effect for the Pd-Au membrane within the pressure range of practical H-2 permeation tests, which are consistent with the previously reported sorption rates hypothesis and results. (C) 2012 Elsevier B.V. All rights reserved.