A generally applicable model was developed for the kinetic analysis of the reaction network in the polyesterification of unsaturated dicarboxylic acids with diols in the presence of homogeneous acid catalysts. The network consists of the esterification reactions as well as the side reactions, i.e. the cis-trans isomerization and the double bond saturation reactions. Rate equations based on plausible reaction mechanisms were derived and the parameters of the rate equations were determined, with non-linear regresssion analysis using the polyesterification of maleic acid with propylene glycol at 140-190 degrees C as a demonstration system. Comparisons of the model predictions with the experimental data showed that the approach provides a reasonable description of the polyesterification network.