The preparation of alumina supported Pd catalysts through a photochemical approach, consisting in the liquid phase photo-deposition (LPPD) technique in the presence of unmodified beta-cyclodextrin (beta CD) as protecting agent, has been here investigated. It was found that it is possible to tune both the Pd nanoparticles size and their distribution over the support surface by changing the concentration of the beta CD used during the photodeposition process. In fact, on increasing the amount of the beta CD, the obtained Pd/Al2O3 samples exhibited Pd nanoparticles (NPs) smaller and more homogeneously distributed over the support, pointing out that the beta CD has a protective effect, avoiding the growth of Pd NPs and their aggregation. It is concluded that LPPD in the presence of unmodified beta-cyclodextrin represents an interesting approach for the preparation of supported Pd catalysts with a controlled metal nanoparticle size and distribution to be used in structure sensitive reactions. (C) 2011 Elsevier B.V. All rights reserved.