Bimetallic Pd-Pt/Al2O3 catalysts were prepared by controlled surface reactions. The reduction of PtCl62- can be made by using as reductant hydrogen preadsorbed on a parent monometallic Pd/Al2O3, catalyst (refilling), or metallic palladium itself (direct redox reaction). Two precursors (Pd(NH3)(4)Cl-2 and Pd(Acac)(2)) were used to prepare the (1 wt % Pd) parent catalyst. The platinum loading is within the range 0.13-0.14 wt %. The characterization of the catalysts was made by hydrogen chemisorption, infrared spectroscopy of adsorbed CO (as probe molecule) and E.X.A.F.S. The two preparation methods lead to different kind of platinum deposit, whatever the palladium parent catalyst. By using preadsorbed hydrogen, platinum can be deposited in decoration on low coordination sites (corners, edges,...) of palladium particles. By direct redox reaction, the deposit of platinum atoms occurs preferentially on the (111) faces of palladium particles. However some sintering can occur, especially during hydrogen treatment in aqueous medium, That sintering is enhanced by chloride ions.