The production of light olefins by alkane dehydrogenation is limited by the thermodynamic equilibrium. The use of membrane reactors for this process enhances alkane conversion by a selective removal of hydrogen from the reaction media. This hydrogen removal results in an equilibrium shift towards the production of olefins. However, hydrogen permeance through Pd-based membranes may be affected by the presence of light olefins. This work evaluates the effect of the composition of propane/propylene mixtures on the hydrogen permeation through Pd-Ag alloyed membranes for propane dehydrogenation. It has been observed that the transient hydrogen permeation decreases in the presence of C-3 species due to coke deposition over the Pd-Ag layer. The permeation decrease has been characterized and quantified as a function of propane/propylene contents in the feed gas and of operation temperature. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.