The kinetics of melt polyesterification of adipic acid with hexamethylene glycol in an equimolar ratio has been studied over a temperature range of 120 degrees C to 150 degrees C in the absence and presence of p-toluene sulphonic acid (PTSA) or diphenylammonium triflate (DPAT) as catalyst. The rate equations for polymerizations fit the rate equations proposed by Tang-Yao for 80-480 min. For acid-catalyzed and non-catalyzed polyesterifications at various temperatures, plots of 1/(1-p) and 1/(1-p)(3/2) have been made against time, respectively. The fits test accuracy was also ensured by the least squares method. The experimental results show that reaction orders are 2.5 and 2 for uncatalyzed and acid-catalyzed reactions, respectively, with up to 97% conversion. The rate constants and activation energies for uncatalyzed and acid-catalyzed reactions were calculated. The activation energies are 45.01 kJ/mol for the self-catalyzed system, 35.32 kJ/mol for DPAT catalyzed system and 31.55 kJ/mol for PTSA catalyzed system. Activation energies are compared to literature data for polyesterification reactions of adipic acid with hexamethylene glycol in equimolar quantities. We found that the catalytic activity of DPAT in polycondensation is similar to that of PTSA.