[en] Carbon-coated ferromagnetic (Fe-Fe 3 C) nanocomposites have been synthesized using solidphase pyrolysis of metal-organic compounds. The structure, morphology and magnetic characteristics of these nanocomposites were investigated by electron microscopy, X-ray diffraction, Raman spectroscopy and magnetometry. The magnetic characteristics such as saturation magnetization and coercivity as well as the specific absorption rate (SAR) make these materials attractive for magnetic hyperthermia applications. Hysteresis loop of the (Fe-Fe 3 C) & C nanocomposites is of special interest as it shows almost square behavior, where Mr/M (200 Oe)= 0.75. The limitation of the magnetic field amplitude and frequency (H⋅ f)≤ 10.625⋅ 10 6 Oe/s makes this factor important that provides a high energy absorption even in case of low magnetic fields. The TEM image, hysteresis loop and heating saturations are shown in figure. Ag-doped lanthanum manganite and carbon-black hybrids have been prepared by physical mixing of modified carbon and Ag-doped LaMnO 3 nanoparticles, followed by sintering at different temperatures. Ag x La 1-x MnO 3 nanoparticles were first synthesized via microwave enhanced chemical precipitation, and the carbon support was modified using graphitization, followed by HNO 3 and ammonia treatments. Microwave assisting yielded in improved uniformity of nanoparticles and reduced time of synthesis, which can become important for practical use of lanthanum manganite nanocomposites.(author)