Polyethylene (PE) powders were grafted by acrylic acid or maleic anhydride/styrene monomers. The elemental surface composition was determined by means of X-ray photoelectron spectroscopy (XPS). Time-of-flight secondary ion mass spectrometry (ToF-SIMS) investigations were carried out to obtain information about the molecular build-up of the grafted polymers. XPS measurements showed the presence of oxygen-containing functional groups on the PE particle surface. The ToF-SIMS spectra gave evidence for polymer chains with alternating maleic anhydride and styrene units. In addition, fragments of polystyrene block segments were found.