The polyesterification of 1,3-(dicarboxymethoxy)benzene with tetraethylene glycol in both equimolar and nonequimolar ratios were studied over the range of 120–160°C in the absence and presence of p-toluenesulphonic acid as catalyst. The experimental results for uncatalyzed reactions agreed quite well with the kinetic equation proposed by Flory. The kinetic equations for acid-catalyzed reactions, however, are in agreement with the kinetic equation proposed by Lin and Hsieh. The kinetic equations were −d[COOH]/dt = k1[COOH]2[OH] and −d[COOH]/dt = k2[COOH]2 for uncatalyzed and acid-catalyzed polyesterfications, respectively. The rate constants for uncatalyzed and acid-catalyzed reactions were calculated by using the method of least squares for various values of initial molar ratio between [OH] and [COOH]. Also, the activation energies were calculated.