The aim of the Letter is to elucidate the nature of metal-support interaction in the 2 wt% Rh/Al2O3 catalyst obtained by annealing Rh-O-Al xerogel at 1113 K in air. XPS, HRTEM, and XRD results reveal that during the Rh-O-Al xerogel annealing in air, rhodium incorporates into forming alumina, which results mostly in Rh4+/delta-Al2O3 solid solution formation. However, in the course of the catalyst reduction at 773 with H-2 and at 823 K with CH4 the Rh4+/delta-Al2O3 solid solution transforms into Rh-Al alloy. The islands of rhodium form oil the Surface of the Rh-Al alloy nanocrystallites if the reduction is slow enough. (c) 2005 Elsevier B.V. All rights reserved.