Passivation of oxide-free silicon nanowires (Si NWs) by the formation of high-quality fluorinated 1-hexadecyne-derived monolayers with varying fluorine content has been investigated. Alkyl chain monolayers (C16H30-xFx) with a varying number of fluorine substituents (x=0, 1, 3, 9, 17) were attached onto hydrogen-terminated silicon (Si-H) surfaces with an effective one-step hydrosilylation. This surface chemistry gives well-defined monolayers on nanowires that have a cylindrical core-shell structure, as characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and static contact angle (SCA) analysis. The monolayers were stable under acidic and basic conditions, as well as under extreme conditions (such as UV exposure), and provide excellent surface passivation, which opens up applications in the fields of field effect transistors, optoelectronics and especially for disease diagnosis. (C) 2016 Published by Elsevier B.V.