Magnetic nanocomposite of Sm/Co/C-system is prepared and characterized. It reveals chemical and thermal stability. SQUID magnetometry is applied to study hysteresis behaviour of the material. Modified Langevin formalism is used to distinguish between ferromagnetic and paramagnetic contribution to magnetization. It is shown that 80 % of low temperature remanence is stable at 350 K and coercive field at this temperature is 140 Oe.