An examination was made of the adsorption of some metallic cluster carbonyls (MCCs), Co2Rh2(CO)12, Co3Rh(CO)12, Co4(CO)12, Ir4(CO)12, Rh6(CO)16, and Ru3(CO)12, from nonaqueous solution onto two typical catalyst supports, ¿-alumina and Aerosil silica. With two MCCs, Co2Rh2(CO)12 and Ir4(CO)12, dispersed metallic catalysts were generated, and a study was made of how the main experimental conditions affected the metallic dispersion. MCC adsorption was more facile on ¿-alumina than on silica and was often assisted by the presence of oxygen. An ir study showed that initial adsorption of Co2Rh2(CO)12 on ¿-alumina occurred with the loss of bridging carbonyls, the remaining carbonyls being progressively lost at temperatures >300 K, while adsorption of Ir4(CO)2 on ¿-alumina resulted in progressive carbonyl loss at 320–620 K. Strong adsorption involves carbonyl loss, probably by ligand exchange with a surface anion, and the effect of oxygen is probably oxidative decarbonylation. Catalysts prepared from Co2Rh2(CO)12 or Ir4(CO)12 were relatively highly dispersed (D ˜ 0.4-1 depending on conditions), and Co2Rh2(CO)12 gave a much higher dispersion than was obtained by conventional impregnation using aqueous salt solutions. MCC adsorption in the presence of oxygen favored higher dispersions.