In this work, we proposed the method for synthesis of nanowires with Mg2Si/Sibased core-shell heterostructure. Silicon nanowires acting as a source of silicon for the silicification reaction were obtained by well-studied metal-stimulated chemical etching of silicon with orientation (100) doped with boron, with a resistivity of 1–10 Ω×cm. A 30 nm thick gold film with an adhesive titanium sublayer 1.5 nm thick was used as the catalytic metal. The etched nanowires had a height of ~10 microns and a diameter of 1.5 microns. The Mg2Si shell was formed using the solid-phase epitaxy method under ultrahigh vacuum conditions. The thickness of the silicide shell was 400–600 nm on the side surfaces of the nanowires.