To study the possibility of the production of branched polypropylene (PP) by a reactive extrusion (REX) route, side chains were introduced on the backbone of a polypropylene material by reacting hexadecylamine with acrylic acid grafted PP. Experiments were carried out both in solution and in the melt, and the products were analyzed by FTIR, elemental analysis, dynamic mechanical, and rheological techniques. Analysis of the FTIR spectra of the samples produced in the solution reactions, at an equal molar ratio of [- NH2]/[-COOH] without catalyst addition and without removal of the by-product, revealed that the formation of imide was increased with increasing the reaction time up to 10 h, while a further increase in reaction time resulted in a reversal of the reaction. In the REX experiments, FTIR analysis showed that the imide formation increased with the [-NH2]/[-COOH] molar ratio. At a molar ratio of one, more imide was present in the REX product than the in-solution one. Elemental analysis suggested that the nitrogen content in the products initially increased with [-NH2]/[-COOH] molar ratio and then reached an almost constant value at molar ratio values of about unity. The glass transition temperature (T(g)) was measured by dynamic mechanical analysis (DMA), and it was found that the attachment of the alkyl chains caused a reduction in T(g) of the products. Finally, rheological measurements showed that the shear viscosity of the products increased with the amine/carboxyl molar ratio at low shear rates and that their moduli were enhanced as a result of the attachment of the alkyl side chains.