The influence of surface oxidation and hydrogen upload into the Pd(0.79)Ag(0.21) membrane on hydrogen permeation was examined by measuring the permeation of: 1) gas-phase H(2) sent from the electrode back-side and 2) electrolytic H2 produced on electrolyte side. It was verified that hydrogen upload into PdAg lattice has positive effect i.e. increases hydrogen permeation, while surface oxides formed during and after electrolysis cycles are the main factors acting on decrease of hydrogen permeation. Particularly, silver oxides are identified as permeation-blocking species. Consequently, several treatments were proposed aiming to reduce electrode deactivation; beside wet chemistry treatments applicable after electrolysis, the in situ electrode reactivation by ultrasonic pulses was presented. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.