The surface of monocrystalline silicon was chemically converted with hydrocarbon to polycrystalline &bgr;‐silicon carbide, and the growth mechanism was investigated by means of14C tracer method. It is shown that the growth of the silicon carbide layer is due to diffusion of silicon through the SiC layer so that the Si&sngbnd;SiC conversion is taking place at the surface of the sample. Dependence of layer thickness on carbidizing time and on hydrocarbon concentration in the carrier gas hydrogen was measured.