Polycyclotrimerization of a flexible aromatic dicyanate with a Schiff base structure was studied by means of differential scanning calorimetry (DSC). The study on dynamic DSC evaluated an apparent activation energy (E(alpha)) of 75.8 kJ/mol and autocatalytic first-order kinetics with rate expression Af(alpha) = 1.96 X 10(5) (1 + 4.39 alpha) (1 - alpha) min(-1). The kinetic feature can be explained by a proposed mechanism consisting of hydroxyl-catalyzed and autocatalytic paths. The lower value of E(alpha) compared with other aromatic dicyanates is due to the electron-withdrawing linkage of the inherent imine (-CH=N) structure. The kinetic feature is affected by the content of the residual impurities (e.g., phenols or absorbed water) in the corresponding sample.