Samples of α-iron and iron carbide (Fe3C) nanoparticle agglomerates (with a typical size of α-iron nanoparticles in the 14-15 nm range) dispersed at a concentration of 0.1 % in nonmagnetic matrix of wax have been prepared. The samples have been characterized by XRD and SEM spectroscopy. Magnetic resonance measurements of the samples, using X-band electron paramagnetic resonance spectrometer, have been carried out in 300-8 K temperature range. A very intense and very broad magnetic resonance line has been recorded in all samples with various weight ratios of α-irons and iron carbides. For samples at room temperature the resonance signal could be fitted by one (for low iron concetration) or two (for high iron concentration) Lorentzian-shape lines: one centered near zero magnetic field (around 20-100 mT), and the other at higher magnetic field (about 520-550 mT). Both lines displayed a strong decrease of their integral intensity with decreasing concentration of iron. With increasing concentration of the Fe3C nanoparticles the intensity and the linewidth of the resonance absorption signal shows an unusual behavior as a function of temperature. The shape of resonance line is changing with temperature; it becomes more flat at lower temperatures. Amplitude of the resonance absorption signal is decreasing with temperature down to 40-60 K and then increasing again with further temperature decrease down to 8 K. The resonance line is shifting with temperature increse towards higher magnetic fields and the integral intensity is increasing.