We report a facile room-temperature synthesis method for a blue-luminescent silicon nanoparticle, whose surface is stabilized with a hexadecanoxyl monolayer. The synthesis of the nanoparticle was performed by the sodium naphthalenide reduction of silicon tetrachloride. Details of characterization with FTIR and H-1 NMR indicated the successful replacement of a surface chloride of the nanoparticle with a hexadecanoxyl group. The use of a surfactant, that is, tetra-n-octylammonium bromide, led to a uniform size distribution, while its absence produced a sample with a large size distribution. The hexadecanoxyl capsule stabilizes the surface of blue-luminescent nanoparticle under ambient conditions even after 1 year. (c) 2008 Elsevier B.V. All rights reserved