In this work, we chemically modified linear low-density polyethylene with maleic anhydride in the molten State using, in a first step, different closed of ultraviolet irradiation to generate hydroperoxide groups, which were highly reactive at the processing temperature. Then, in a second reactive extrusion step, maleic anhydride was grafted to the linear low-density polyethylene under different processing conditions. Characterization of the modified and unmodified linear low-density polyethylene material was performed with Fourier transform infrared spectroscopy, differential scanning calorimetry, and nuclear magnetic resonance. (C) 2009 Wiley, Periodicals, Inc. J Appl Polym Sci 113: 3125-3129, 2009