A variety of carbon-based materials attracted much attention recently due to unusual magnetic properties, including ferromagnetic (FM) behavior and possibility of a long-range magnetic order. Some of them exhibit the FM-like properties even well above the room temperature [1]. Applications of such materials, metal-free or containing small amounts of metallic inclusions, are expected to spread from spintronics and light magnets in technics to biology and medicine [1, 2]. Here we investigate magnetic properties of powder and glassy samples containing carbon nanoparticles, not intentionally doped or doped with Ag, Au and Co. The purpose of the work is macroscopic information on the magnetic irreversibility, hysteresis and saturation magnetization, and such microscopic data as distribution of the magnetization over the particle volume, values of the localized magnetic moments, their spacing and interaction. The atomic force microscopy data give evidence for a broad size distribution of the carbon particles, given by the average and the maximum radii of ~ 60 and ~ 110 nm, respectively. Magnetization M (T, B) of the samples is investigated between T ~ 3 − 300 K in magnetic fields B up to 5 T with the SQUID magnetometer. The dependence of M (T) in low fields of B ~ 1 − 50 mT exhibits large irreversibility or deviation of zero-field cooled and field-cooled magnetization already at the room temperature. The magnetic irreversibility is suppressed completely at B > BK, where the mean anisotropy field BK ~ 1 T. The dependence of M (B) saturates above 2 T at high temperatures, but deviates from the saturation behavior below ~ 50 − 150 K. Magnetic hysteresis is observed already at 300 K. Hysteresis curves are characterized by a power-law temperature decay of the coercive field, Bc (T), with the exponent n ≈ 0.8, zero-temperature value Bc (0) increasing from 36 − 52 mT up to 80 mT in the Co-doped sample, and the maximum blocking temperature Tb ≈ 400 − 580 K. The relation Bc (0) << BK is typical of magnetization reversal of single-domain particles by curling. On the other hand, the value of n ≈ 0.8 indicates close proximity of the particle radii, R, to the single-domain limit. A detailed analysis of Bc (0) and the saturation magnetization yields a thickness of the near-surface layer of the particles, h, filled with localized magnetic moments μ1 ≈ μB, to be close to the average distance between the moments, a ≈ h ~ 1 nm. The properties above are consistent with the origin of magnetism in nanocarbon preferably due to intrinsic surface defects. However, in the Co-doped sample the Co ion moments and/or clusters may play a significant role in formation of the magnetic properties, as well. Eventually, the FM Curie temperature, TC, evaluated with a model of twodimensional network of point defects or layered magnets [3, 4], satisfies the relation of TC > Tb, which is in line with the defect nature of the unusual magnetism of nanocarbon.