New thermally stable polyamides were prepared by low‐temperature polycondensation in N,N‐dimethylacetamide from perchloro‐4,4′‐dichloroformylbiphenyl and various aromatic and aliphatic diamines. The polymers were characterized by infrared spectroscopy, elemental analysis, TGA, and DSC and found to show higher thermal stability than other nonchlorinated polyamides.