We investigated the intermolecular mechanism and kinetics of the synthesis of a novel biodegradable protein-based plastic from bovine serum albumin under suberitical water conditions using batch reactors. The reaction mechanism could be viewed as a chain reaction stabilized by the formation of intermolecular disulfide bonds. The kinetic analysis was based on non-steady-state kinetics using a theoretical model developed in one of our previous works. The activation energy and pre-exponential factor were found to be 7.2 kJ/mol and 0.9 s(-1), respectively. These low values signify that the reaction is relatively temperature-insensitive with some diffusion limitation.