A number of carbosilane dendrimers derivatised on their external surface by silanol groups have been synthesized and characterised. The new molecules are prepared by repetitive hydrosilation/alkenylation reactions, and then careful hydrolysis of Si-Cl groups in one of two ways produces dendrimers with external Si-OH groups. Various molecules with three, four and eight vinyl groups were used as the starting molecules to produce dendrimers of different sizes. The first-generation dendrimer based on a tetravinylsilane core has been characterised by single crystal X-ray diffraction.