Hydrogen isotope selectivity of palladium membranes has long been known and studied, but the emergence of vanadium-based membranes as a low-cost alternative naturally inspires curiosity as to whether these membranes exhibit similar properties. Accordingly, experiments to calculate the permeability of hydrogen and deuterium through a palladium-coated vanadium membrane at 300 degrees C were undertaken, and they revealed that hydrogen permeates at a rate 1.5 x faster than deuterium. With hydrogen absorption experiments at the same temperature showing very little difference in the amount of each isotope absorbed over a wide pressure range, it can be concluded that atomic hydrogen diffuses through vanadium 1.5 x faster than atomic deuterium. In practice, this gives rise to a significant separation factor, with deuterium being depleted in the permeate stream, but enriched in the retentate stream. Creating a cascading series of membranes, with successive retentate streams combined, will allow the deuterium concentration to be enriched far beyond the natural value of 0.015%. This work suggests that further work is warranted to explore whether this separation factor can be enhanced (e.g., through alloying), and to demonstrate a cascading membrane system to deliver high purity deuterium from a natural hydrogen source. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.