Aromatic polyesters with isophthaloyl, pyridine-2,6-dicarbonyl and pyridine,2,5-dicarbonyl units in the main chain were synthesized and were characterized by inverse gas chromatography (i.g.c.). The polyesters containing complex ’triad’ monomers and aromatic diols were obtained by high temperature solution polycondensation. In order to investigate whether the surfaces of polycondensates act as Lewis acids or Lewis bases, the donor-acceptor interactions between various probe molecules and polyesters have been studied by means of i.g.c. Because the measurements were carried out at different temperatures, we were able to determine parameters K-A and K-B, which describe the donor-acceptor properties of the stationary phase. One polyester without pyridine units was amphoteric with slight predominance of Lewis-basic behaviour. Polymers containing pyridine units may be considered as Lewis bases. The glass transition temperatures of two polymers have also been determined by i.g.c.