A process of high-pressure torsion (HPT) was used to produce an ultrafine-grained Pd-Ag alloy, and to improve mechanical property and hydrogen permeability simultaneously. Hardness values of the HPT-processed sample were much higher than those of a cold rolled sample which is strengthened by dislocation accumulation. Additionally, in contrast to the degradation of hydrogen permeability in the cold-rolled sample due to a high density of dislocations which act as trapping sites of hydrogen atoms, the hydrogen permeability in the HPT-processed sample was improved due to a high density of high angle grain boundaries which act as a fast diffusion path. The ultrafine-grained structure in the Pd-Ag alloy was retained during permeation testing at 300 degrees C due to the addition of silver. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.