The membranes studied have been able to preferentially separate water vapour from other gases. The maximum performance is achieved at temperatures below 100 ºC and high steam contents. By contrast, on increasing the temperature above 100 ºC the performance decreases rapidly. However, water vapour is still preferentially separated up to 300 ºC. For example, for a steam content of ≈24 %, the steam to hydrogen selectivity is ≈10 and ≈2.5 at 75 ºC and 225 ºC, respectively. The selectivity can be further increase by functionalising the surface of the membranes with particular hydrophilic groups. Thus, for the same conditions previously mentioned, the steam to hydrogen selectivity increases from ≈10 to ≈85 and from ≈2.5 to ≈4. For other gases such as CO and CO2, the performance of these membranes would be even greater. The dissemination of these results and the data linked to them will be shortly published in open access scientific publications and repositories.