The polarity of a hard Fischer-Tropsch paraffin wax was improved through grafting of maleic anhydride (MA) initiated by dibenzoyl peroxide (DBP), which is reflected by a significant increase in the polar component of the surface free energy. MA and DBP concentrations of 3 wt % each are sufficient for significant modification of the polarity of the wax. FTIR spectra confirm the presence of anhydride groups on the wax chains, while gel permeation chromatograms show the development of a low molecular weight peak, which may be indicative of wax degradation. The grafting of wax by MA decreases the specific enthalpy of melting, as determined through differential scanning calorimetry. (C) 2004 Wiley Periodicals, Inc.