Abstract A feasibility study has been made of the synthesis of high molecular weight polyamides under mild conditions by aminolysis of bis-nitrophenyl esters of pyridinecarboxylic acids, and some features of the reactions have been investigated. Polyamides with reduced viscosities of 0·034–0·095 m 3/kg have been prepared. Activation of ester groups in these diesters is obtained by introducing the electron acceptor NO 2 group into the phenol residue. A comparative study was made of the extent to which the structure of some heterocyclic diesters influences the yield and viscosity properties of the resulting polyamides. A relationship was found between the electrophility of the ester carbonyl group and the p K a of alcohols formed in the aminolysis: as in the case of aromatic diesters [1, 2] the diester activity increases with increasing acidity of the alcohols. Thermodynamic properties of the synthesized polyamides were investigated and their melting, within a narrow temperature interval, determined.