The influence of irradiation by pulsed ion beam on the morphology, structure, and chemical composition of a composite based on multiwalled carbon nanotubes (MWCNTs) and tin dioxide (SnO 2-x @MWCNTs) was investigated. It has been established that irradiation of the composite by pulsed ion beam leads to the formation of Sn/SnO x core-shell nanoparticles, which adhere to the surface of the MWCNTs. The “core” is metallic Sn and the “shell” is amorphous SnO x . A uniform distribution of Sn/SnO x nanoparticles on the surface of the MWCNTs was noted, and the maximal concentration of tin in both volume and surface layer was achieved by triple irradiation with an energy density of 0.5 J/cm 2 . This composite exhibited good electrochemical performance as an anode material for lithium-ion batteries, delivering 1494 mA h g −1 as a first discharge capacity and 634 mA h g −1 discharge capacity (72% capacity retention) after 30 cycles of charge/discharge.