Nanoparticles of palladium were synthesized by a 'ship-in-a-bottle' technique in supercages of Y-zeolite. The ions of Pd2+ were introduced into the zeolite by ionexchange between PdCl2 and NaY zeolite. They were then reduced by an electrochemical method and assembled to form nanoparticals by admission and release of CO. The electrode of palladium-loading zeolite film was characterized by cyclic voltammetry, and the adsorption of carbon monoxide on the electrode was studied using in situ electrochemical FTIR reflection spectroscopy. A novel phenomenon of enhanced IR absorption (EIRA) was observed for the first time. In comparison with CO adsorbed on a massive I'd electrode, the IR absorption of CO adsorbed on nanoparticles of Pd confined in supercages of Y-zeolite has been enhanced to about 51 times.