This invention relates to a macromonomer and a method for its preparation. The macromonomer has one or more silicon-bonded hydrogen atoms at one molecular chain terminal, and one or more aliphatically unsaturated silicon-bonded organic groups at the other molecular chain terminal. This invention further relates to a method of forming a hyperbranched polymer by polymerizing the macromonomer with a group VIII metal catalyst. The hyperbranched polymers can be used as surfactants, gelling agents, drug delivery systems, and polymeric absorbents.