Functionalization of polypropylene (PP) has been investigated using the high-temperature route. The advantage of the high-temperature functionalization is the introduction of cheaper, long-term stable and environmentally friendly routes for generating surface active groups on PP. In this regard, extensive experimental work was undertaken to investigate the influence of the high-temperature (40-360 degrees C) treatment, reaction time, and inert/oxidative gas environments on generation of functional groups on PP. The thermal gravimetric analysis and differential scanning calorimeter techniques were used to study the changes in the temperature of melting/crystallization and the crystallinity of the treated PP samples. Scanning electron microscopic analysis showed that the high-temperature treatment under inert/oxidative affects the surface/morphology of PP samples. Fourier transform infrared (FTIR) was used to examine the surface species formation and the stability of functional groups. FTIR results of the thermally treated PP showed the selective formation of monosubstituted alkenes under inert atmosphere, while the formation of hydroperoxides, carbonyl, lactones, and substituted alkenes stable species was observed under oxidative atmosphere. The changes in the molecular weight of the treated PP under different conditions were evaluated using high-temperature gel permeation chromatography (HTGPC) technique. The extent of functionalization of PP up to 20% or more could be obtained by using the different oxidation conditions. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 1-11, 2012