The share of high performance thermoplastic composites within airframe structures is relatively small, although these materials offer the potential of very short cycle time processing. Only PEEK and PPS are used for primary structure applications, however PEEK has a high price and PPS cannot deliver the whole range of properties. This investigation focuses on the development of thermoplastic polymer blends on the basis of polyphenylene suflide (PPS) and polyether sulfone (PESU) as substitutes for high-cost polyether ether ketone (PEEK) and neat PPS in fiber reinforced composites. It is targeted to deepen the understanding of PPS/PESU blends processing and resulting properties. First studies, utilizing injection molding processing, revealed a strong dependency of the resulting property profile on processing conditions and the relative polymer portions [1]. In this study we focus on the relationship between the rheological behavior and resulting morphology of PPS/PESU blend films, made via a film casting/extrusion process. Properties especially affected by the blends morphologies are the mechanical and thermo-mechanical behavior as well as the resistance towards liquid media. Analytical effort is primary focused on characterization of the crystallization kinetics, morphology changes in single films and solid plates and the influences on the mechanical (strength and toughness) and thermo-mechanical (storage modulus at high temperature) properties. Additional attention is paid to thermal annealing of PPS/PESU samples, to significantly increase the blends performance. A primary finding was that the degree of crystallization increases with higher PPS fractions, strongly affecting the overall performance and thus depends on extrusion parameters, consolidation conditions and thermal treatment of tested samples. Conclusions of this work evidence the high potential of tailored PPS/PESU blends for film extrusion and stacking processes, partly outperforming PEEK and neat PPS.