The hydrolysis of polyethylene terephthalate (PET) pellets in nitric acid was investigated to determine the kinetic parameters. Experiments were conducted with cylindrical shaped pellets in 13M nitric acid at 80, 90, and 100degreesC respectively. Also, an experiment was conducted with a waste PET bottle sheet in 9.5M nitric acid at 100degreesC. The kinetics of the reaction was explained by the shrinking core model with surface chemical reaction as rate controlling step and accounting for surface area reduction due to the deposition of the product terephathalic acid (TPA) on the reaction surface. The activation energy for the reaction was found to be 135 kJ/mol. (C) 2003 Wiley Periodicals, Inc.