The permeation behavior of a 2.0 mu m thick Pd95Ag5/ceramic composite membrane was investigated between 403 K and 823 K. Above 460 K H-2 fluxes can be represented by an Arrhenius law with J(H2) = 1.6 +/- 0.1 Mol m(-2) s(-1) exp [-9.0 +/- 0.2 kJ mol(-1)/RT] at Delta P-H2 = 100 kPa with the initial ideal H-2/N-2 selectivity exceeding 4700 at 823 K. A discontinuity occurred in the H-2 flux between 455 K and 420 K due to the opening of the miscibility gap in the Pd95Ag5Hx phase diagram and the appearance of the beta Pd95Ag5 hydride phase. Below 420K H-2 fluxes can be represented by another Arrhenius law with J(H2) = 1.7 +/- 0.2 Mol m(-2) s(-1) exp [-7.2 +/- 0.3 kJ mol(-1) /RT] at Delta P-H2 = 100 kPa. Activation energies are consistent with diffusion limited H2 transport both above and below the permeation discontinuity. A gradual shift towards linear pressure dependence with decreasing temperature is attributed to an increasing impact of the mass flow resistance of the 2 mm thick ceramic support on the H-2 permeation rates at low temperatures. A steeper increase of the pressure exponent n upon appearance of the beta Pd95Ag5 hydride is associated with the lower hydrogen activity in this phase. The membrane exhibited good stability during 20 temperature cycles between 473 K and 673 K in H-2 atmosphere and 3 cycles down to room temperature in N-2, resulting only in a slight increase of the N-2 leak rate from 0.44 x 10(-3) Mol m(-2) s(-1) to 0.54 x 10(-3) Mol m(-2) s(-1) at 673 K and Delta P-N2 = 100 kPa. Monitoring of H-2 on the permeate side after switching from H-2 feed to N-2 purge streams showed that between 5 h at 673 K and 9 h at 523 K were required for a complete release of H-2 from the composite membrane. Analysis of the emitted H-2 volumes showed that the H-2 release on the permeate side was limited largely by the mass flow resistance of the porous ceramic support. H-2 released on the membrane feed side exceeded that on the permeate side by 1-2 orders of magnitude and originated mainly from the stainless steel reactor shell. As a consequence the hydrogen content of supported Pd and PdAg layers could remain above the threshold for embrittlement after switching to inert atmospheres if not sufficient time is allowed for H-2 release before cooling. (C) 2008 Elsevier B.V. All rights reserved.