To improve characteristics of hydrophobic catalysts for hydrogen isotope separation between hydrogen and water which is a key reaction for water detritiation and heavy water production, monodispersed Pt3M bimetal hydrophobic catalysts were fabricated. The average diameters of Pt3M nanoparticles ranged from 2.2 nm to 2.6 nm. The lattice parameters of Pt3M were 3.87 angstrom, 3.83 angstrom, 3.78 angstrom and 3.90 angstrom, respectively. All compositions were well-controlled to the similar value. The addition of the metallic Fe, Ni, Cr, and Co hindered the oxidation of the metallic Pt during the preparation of Pt3MC catalysts. The catalytic activities for HID isotope separation increased in the following order: Pt/C < Pt3Ni/C approximate to Pt3CoC < Pt3Fe/C < Pt3Cr/C. Catalytic performance tests demonstrated that selection of Pt3M bimetal is a very effective approach to improve hydrophobic catalytic. Finally, the enhanced activities of Pt3M bimetals over Pt were discussed by different mechanisms. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.