A generally applicable stoichiometric and kinetic model was developed for the polymerization of dimer fatty acids with ethylenediamine in the presence of phosphoric acid as catalyst. Rate equation used is based on second order and the temperatures are between 405 and 475 K with mixing rate of 75 rpm. The parameters of the rate equations are determined using nonlinear regression analysis. Comparison of the model predictions with the experimental data show that the approach is useful in predicting the polymerization kinetic. Equilibrium constant changes from 2.432 to 17.765. Frequency factor and activation energy for forward rate constant are 362306102.681 kg mol(-1) min(-1) and 83.24 kJ mol(-1), respectively. The equilibrium constant is independent of temperature with frequency factor and activation energy values of 17317.97 and 28.65 kJ mol(-1), respectively. (C) 2004 Published by Elsevier B.V.