Abstract. Hydrogen-passivated silicon nanochains were synthesized by pulsed laser ablation of silicon target in hydrogen gas atmosphere at room temperature. When the hydrogen gas pressure was higher than 670Pa, nanochains, which have crystalline silicon core, were formed. Transmission electron microscopy showed the silicon nanochains consist of connections of silicon nanocrystals with mean diameter of 4.6 nm. It is of great interest that the silicon nanochain has crystalline structure without any intentional annealing process. Optical properties of the hydrogen-passivated silicon nanochains were presented.