This paper describes a new solution route for the preparation of silicon nanoparticles functionalized at the surface using potassium incorporated in graphite (C8K) as reducing agent of silicon tetrachloride (SiCl4). In a first step, chloride,capped silicon nanoparticles were obtained. They allowed an easy access, in a second step, to a range of surface functionalities by simple nucleophilic substitutions: hydroxy, alkyl, alkoxy or amino groups. They were characterized by FTIR, H-1, C-13 and Si-29 NMR. A mean diameter of 13 nm, was found for these particles. To cite this article: D. Arquier et al., C. R. Chimie 10 (2007). (c) 2007 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.