The compatibilization of the polymer blend polyamide 6/poly(phenylene oxide) (PA-6/PPO) system has been studied using the reactive random copolymer styrene-maleic anhydride (SMA) as a compatibilizer precursor. SMA is miscible with PPO when the MA content of SMA is not higher than 8 wt %. The anhydride groups of SMA react with the amino end groups of PA-6 during melt blending to form a graft copolymer at the interface with a compatibilizing effect as a result. Two different blending procedures were compared to each other and the compatibilizing effect of the added SMA was evaluated for a matrix/dispersed particle type of morphology. The effect of the different material parameters such as the functionality of SMA (wt % MA in SMA) and the molecular weight of PA-6, and blending parameters such as the extrusion time was analyzed with respect to the blend phase morphology. Finally, the amount of reacted MA groups in the blends PA-6/(PPO/SMA) was determined with FTIR after the use of an extraction method to remove the PA-6 matrix phase. The comparison between the morphological data (particle size reduction of the dispersed PPO/SMA phase) and the FTIR data (amount of reacted MA groups) of the blends considered, turned out to be very logical.