Chains of crystalline-Si nanospheres (Si nanochains), in which Si nanocrystallites are connected by amorphous Si oxide periodically in nearly equal spacing forming a chain-like one-dimensional structure, have been fabricated via a self-organized formation process. In this paper, we review our recent studies and extend results on structural analysis, formation mechanism and properties of Si nanochains. The structure have been revealed by transmission electron microscopy-based approaches including high-resolution imaging, energy-filtered imaging and energy-dispersive x-ray fluorescence analysis. The one-dimensional growth was attributed to the well-known vapor-liquid-solid mechanism. A formation mechanism of the chain-like structure was proposed: periodical change in diameter in Si nanowire growth and self-limiting surface oxidation during growth. The former was evidenced through numerical simulations of nanowire growth catalyzed by a molten droplet, and the latter through energy-filtered transmission electron microscopy observations. We also developed a method of high-yield chain growth by adding metal impurities such as Pb to the Au catalyst. By adding such metal impurities, a periodic instability in the wetting angle of the catalysts was promoted. Using the dense chain samples, we observed a phonon-confinement effect in the Si nanocrystallites by Raman scattering and also found that the Si nanocrystallites in the nanochains were under compressive stress. We also observed photoluminescence in visible-light region, and the luminescence was tentatively attributed to the exciton recombination in the Si oxide. Electronic transport property of the Si nanochains characterized well the chain-like feature: staircases were observed in I-V curves. The result opens possibility that Si nanochains can be used as components of single-electron devices. Finally, it was demonstrated that more complex nanostructures can be fabricated using Si nanochains as templates. [DOI: 10.1380/ejssnt.2005.131]