Dendritic carbosilanes have been prepared by the use of 2,4,6,8-tetramethyl-2,4,6,8-tetravinyl-2,4,6,8-tetrasila-1,3,5,7-tetraoxacyclooctane (CH 2CHMeSiO) 4 and 1,2-bis(triallylsilyl)ethane ((CH 2CHCH 2) 3SiCH 2) 2 as core molecules, diallylmethylsilyl groups ((CH 2CHCH 2) 2MeSi) as building blocks and bisphenylethynylmethylsilyl groups ((PhCC) 2MeSi) as terminating groups. The phenylethynyl-group-containing terminal generation is produced by the reaction of the chlorosilylated generation with lithium phenylacethylide. The reaction of dicobalt octacarbonyl Co 2(CO) 8 with phenylethynyl groups gave the corresponding phenylethynyl hexacarbonyl complexes (2Co 2(CO) 6·(PhCC) 2MeSidendimer) on the periphery. The yields of the prepared dendrimers with phenylethynyl terminal groups and their cobalt carbonyl complexes are obtained nearly quantitatively. They are characterized by the use of spectroscopic analyses ( 1H-, and 13C-NMR, UV and IR) as well as MALDI mass spectroscopy and elemental analysis.