Pt/SDBC catalysts, which are used for the hydrogen-water isotopic exchange reaction, were prepared. Nitrogen adsorption and hydrogen chemisorption measurements have been carried out to investigate the effects of the physical properties of SDBC. Dispersion of platinum particles depended on the physical properties, i.e., specific surface area and pore structure of SDBC. As the supported platinum area increases, the catalytic activity of Pt/SDBC for the hydrogen-water vapor isotopic exchange reaction increases. It indicates that the hydrogen chemisorption measurement can be used to estimate the catalytic activities of Pt/SDBC catalysts. It was not observed that the particle size of supported platinum affected the specific reaction rate at 60℃. It implies that this reaction is structure insensitive.