Six new polyamides 5a-f containing flexible trimethylene segments in the main chain were synthesized through the direct polycondensation reaction of 1,3-(4-carboxy phenoxy) propane 3 with six derivatives of aromatic diamines 4a-f in a medium consisting of N-methyl-2-pyrolidone, triphenyl phosphite, calcium chloride, and pyridine. The polycondensation reaction produced a series of novel polyamides containing flexible trimethylene segments in the main chain in high yield with inherent viscosities between 0.32 and 0.68 dL/g. The resulted polymers were fully characterized by means of FTIR spectroscopy, elemental analyses, inherent viscosity, and solubility tests. Thermal properties of these polymers were investigated by using thermal gravimetric analysis (TGA) and differential thermal gravimetric (DTG). The glass-transition temperatures of these polyamides were recorded between 165 and 190 degrees C by differential scanning calorimetry, and the 10% weight loss temperatures were ranging from 360 to 430 degrees C under nitrogen. 1,3-(4-Carboxy phenoxy) propane 3 was prepared from the reaction of 4-hydroxy benzoic acid 1 with 1,3-dibromo propane 2 in the presence of NaOH solution. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 1769-1774, 2009