The sintering behavior of Pt particles on layered Al2O3 was investigated. Layered Al2O3 was prepared by calcination of a commercially available aluminum hydroxide. The growth of Pt particles on layered Al2O3 was suppressed even in an oxidizing atmosphere at above 1000 degrees C, and the particle size was greatly affected by the pore diameter of the layered Al2O3. On the other hand, the particle size of platinum on gamma-Al2O3 was drastically increased. The diameters and the supported states of Pt particles were evaluated by transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), and chemisorption of carbon monoxide. The platinum particles in a highly dispersed state were captured in the pores of layered Al2O3, so the space for the particles for aggregation or migration was limited. (C) 2008 Elsevier B.V. All rights reserved.