A tercet molecular nanocomposite is a ternary miscible polymer system in which a miscible blend of two flexible polymers is molecularly reinforced at nanometre level by a rigid-rod macromolecule and the tercet molecular nanocomposite demonstrates properties better than those of the constituent flexible polymers and their blend. A tercet molecular nanocomposite of a blend of flexible polyamide-6 (PA6) and polyamide-6,6 (PA6,6) molecularly reinforced at the nanometre level by a rigid-rod poly-p-phenylene-terephthalamide (PPTA) has been processed by coagulating a sulfuric acid solution of the components in water. This study reports miscibility, structure and properties of PPTA/[PA6/PA6,6] tercet molecular nanocomposites. Miscibility has been established by recording single intermediate glass transition temperatures by differential scanning calorimetry. Homogeneous morphology and dispersion of PPTA in [PA-6/PA-6,6] below 5 nanometre level has been established by scanning electron microscopy. Intermolecular interactions dispersing PPTA in [PA-6/PA-6,6] below the 5 nm level by imparting miscible homogeneous morphology and have been identified by Fourier transform infra red (FTIR) spectroscopy. Improved tensile mechanical properties of the tercet molecular nanocomposite, compared to those of the constituent flexible polymer blend, have been established by universal testing machine. [ABSTRACT FROM AUTHOR]