Abstract: The catalytic activities of various Pt/C catalysts to hydrogen-water isotopic exchange reaction were measured by method of co-current flow for hydrogen and water vapor and compared with Pt/SBD catalyst. Experimental results for H2-HDO reaction show that surface modification of carbon supports improve the activity of Pt/C catalysts nearly by a factor of two, but all of the Pt/C catalysts have the same reaction order of 0.77±0.05 to the reactant of water vapor and the same activation energies, which are much lower than those ones of unsupported platinum catalysts. This suggests that support modification don’t change the reaction mechanism and activity increase is owing to the increased dispersion of platinum.