A series of polyamide (PA)/montmorillonite nanocomposites containing pyrazine moiety in the main chain were synthesized by a convenient solution intercalation technique. PA 3 as a source of polymer matrix was synthesized by the direct polycondensation reaction of pyrazine-2,3-dicarboxylic acid 1 with 4,4′-diaminodiphenyl sulfone 2 in the presence of triphenyl phosphite, CaCl2, pyridine, and N-methyl-2-pyrrolidone. The resulting nanocomposite films were characterized by Fourier transform infrared spectra, X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis (TGA). The results showed that organo-modified clay was dispersed homogeneously in the PA matrix. TGA indicated an enhancement of thermal stability of new nanocomposites compared with the pure polymer.