4,4 "-Diamino-5＇-phenyl-or 4-alkoxyphenyl-m-terphenyl and 4,4 "-dicarboxy-5＇-phenyl-m-terphenyl were synthesized through pyrylium salts and used for the preparation of rigid-rod polyamides and polyimides. The polymers were characterized by inherent viscosity, elemental analysis, FT-IR, UV-vis, H-1 NMR, C-13 NMR, X-ray, DSC, TMA, TGA, isothermal gravimetric analysis, and moisture absorption. It was shown that the presence of the 4-alkoxyphenyl pendent groups enhanced remarkably the solubility of polymers as well as reduced the T-g＇s and thermal stability. In addition, the polyamide bearing 4-(dodecyloxy)phenyl side groups displayed softening.