Nanoindentation has been utilised to track the mechanical effects of hydrogen on palladium foils over a range of hydrogen concentrations. The miscibility gap in the palladium-hydrogen system yields discrete phases over a range of compositions. It is shown that nanoindentation can measure the extent of hydrogen-induced phase transformations across the film thickness after hydrogen removal, with the alpha -> beta -> alpha phase transformations yielding a similar to 50% increase in local hardness. Interstitial hydrogen was observed to promote work hardening in beta phase regions, and a similar to 75% increase in hardness was observed in regions where the alpha phase was saturated with hydrogen. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.