Innovating in the area of engineering thermoplastics for lunar environment applications requires specific attention to a number of conditions, including: extreme temperature changes (- 200 °C to + 150 °C), high-energy radiation, presence of abrasive and electrostatic nanoscale dust, adequate outgassing and mechanical properties. High-performance thermoplastics are promising candidates for such an application, combining lightness, reparability and remarkable thermal, chemical and mechanical resistance. In this work, polyetheretherketone (PEEK) is melt-blended with meta-polyetherimide (meta-PEI) over the full composition spectrum. The thermal behavior, including the thermal degradation characteristics, are examined in detail and all the blends show a complete miscibility. In order to tailor the mechanical and thermal resistance, PEEK/meta-PEI hybrids are also blended with para-polyetherimide (para-PEI) or polyphenylsulfone (PPSU) over a range of compositions.