Abstract: Pt/C catalysts with isopropanol as both dispersant and reducing agent were synthesized by microwave-irradiated polyol method. The microstructures of the catalysts were characterized by XRD and TEM. The effects of capping agents, pH and heating rate on Pt particle size were studied. Then Pt/C catalysts were loaded on foam nickel with polytetrafluoroethylene latex to obtain hydrophobic catalysts, and their catalytic activities for hydrogen-water liquid phase exchange reaction were investigated. The results show that compared to the non-capped Pt/C catalysts, the average size of Pt particles in sodium acetate, sodium glycollate and disodium hydrogen citrate capped Pt/C catalysts decreases from 4.4 nm to 2.3, 2.5, and 2.3 nm respectively, and the agglomeration of Pt particles becomes obscure. The mean size of Pt particles in Pt/C catalysts decreases evidently with the increasing of the heating rate. However, the mean sizes of Pt particles in the Pt/C catalysts prepared with different pH of the synthesis solution are similar. The activity of the hydrophobic catalysts with capping agents is high for hydrogen-water liquid exchange reaction, and is enhanced by decreasing the average particle size, in the range of 2.3-4.4 nm.