To achieve silicon functionalization for the development of hybrid devices, multifunctional molecules may be employed to attach to the silicon surfaces. It is important to get a fundamental understanding about the molecule/silicon interface chemistry and the binding configuration. The surface chemistry of 3-chloropropyne (HC C-CH2Cl) on the Si(111)-(7 x 7) surface, as a model system for understanding the interaction of the multifunctional molecules with a silicon surface, was studied by X-ray photoelectron spectroscopy (XPS), high-resolution electron energy loss spectroscopy (HREELS), and density functional theory (DFT). The 3-chloropropyne adsorbs molecularly on the silicon surface at 110 K. A chemical reaction clearly occurs such that 3-choloropropyne bonds onto the Si(111)-(7 x 7) surface at room temperature by forming C Si linkage through the cleavage of C-Cl bond, and preserving the ethyne C C triple bond. This functionalized silicon surface may act as an intermediate for the growth of multiple organic layers by further attaching other functional molecules.