The hydrogen isotope exchange reaction between hydrogen and water is a key process in water detritiation and heavy water production. To improve the characteristics of hydrophobic catalysts for this type of reaction, foamed and cellular structures of hydrophobic catalysts were successfully prepared by adding a blowing agent. The mean particle size of Pt nanoparticles was 2.3 nm. The proportions of elemental Pt and Pt oxides were 62% and 38%, respectively. The addition of polymethyl methacrylate powder decreased internal diffusion of water vapor and hydrogen inside the catalyst and improved active site utilization. As a result, the catalytic activities of the hydrophobic catalysts are significantly higher than those of conventional hydrophobic catalysts for hydrogen isotope exchange. All catalysts exhibited excellent hydrophobic performances after 30 days of testing. It was reasonable to mix Pt/C catalysts, polytetrafluoroethene and polymethyl methacrylate in a ratio of 1:2:1 before hydrophobic treatment. Finally, the mechanisms of hydrogen water diffusion and exchange were investigated. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.