Hydrosilylation reaction of allylacetate (AA) with octakis(dimethylsiloxy)octasilsesquioxane [(HSiMe2O)8(SiO1.5)8] was efficiently catalyzed by chloro(1,5-cyclooctadiene)iridium(I) dimer [Ir(μ-Cl)(COD)]2. The effects of the catalyst amounts and the reaction conditions on the conversion and the product selectivity were investigated. [Ir(μ-Cl)(COD)]2 catalyst was also applied to the hydrosilylation