Magnetic particles Fe@C were chemically modified with dibenzo-18-crown-6, dibenzo-21-crown-7 and dibenzo-24-crown-8 through the C-C bond formation using diazonium salts of the corresponding crown ethers. It has been shown that the ability of Fe@C-dibenzocrown ether composites for sorbtion of Yb3+ cations from 0.1 M hydrochloric acid solutions increased from 0 to 90.9-100 %, relative to dibenzocrown ether.