A series of rigid-rod polyamides and polyimides containing p-terphenyl or p-quinquephenyl moieties in backbone as well as naphthyl pendent groups were synthesized from two new aromatic diamines. The polymers were characterized by inherent viscosity, elemental analysis, FT-IR, H-1-NMR, C-13-NMR, X-ray, differential scanning calorimetry (DSC), thermomechanical analysis (TMA), thermal gravimetric analysis (TGA), isothermal gravimetric analysis, and moisture absorption. All polymers were amorphous and displayed T-g values at 304-337 degrees C. Polyamides dissolved upon heating in polar aprotic solvents containing LiCl as well as CCl3COOH, whereas polyimides were partially soluble in these solvents. No weight loss was observed up to 377-422 degrees C in N-2 and 355-397 degrees C in air. The anaerobic char yields were 57-69% at 800 degrees C.