AbstractBlends of poly(ether ether ketone) (PEEK) and bisphenol‐A polyarylate (PAr) were directly prepared during the plasticization step of an injection molding machine and their solid‐state and mechanical behaviors were studied. Despite the fact that PEEK‐rich blends were apparently miscible by differential scanning calorimetry (DSC), from the dynamic‐mechanical analysis (DMTA) results all the blends were composed of (a) a crystalline PEEK phase, (b) a practically pure amorphous PEEK phase, and (c) a PAr‐rich phase richer in PEEK as the PEEK content in the blends increased. Annealed blends showed a poor mechanical performance in the PAr‐rich region, but the PEEK‐rich blends showed additive modulus of elasticity and tensile strength, and ductility and impact strength values similar to those of the highest of the two pure components. All the as‐molded low‐crystalline blends presented a synergistic behavior in the modulus of elasticity, as well as, surprisingly, in ductility and impact strength in the intermediate and slightly majority PEEK compositions. The different mechanical response of the components in fine dispersed phases and in macroscopic tensile specimens may account for the observed results.