XIPERM composite membrane tubes are ultra-thin, highly selective, highly stable, and highly permeable reinforced membrane tubes based on a perfluorosulfonic acid (PFSA) ionomer. The reinforcement layer is a porous substrate integrated into the structure of the membrane to provide enhanced mechanical properties. The enhanced mechanical properties allow the XIPERM™ tubes to be produced with much thinner walls than standard extruded tubes, providing higher permeability of polar compounds without sacrificing strength. The XIPERM tubes are required in applications where thermal and chemical stability are critical. This includes applications such as fuel cell humidifiers and analytical gas conditioning.