The depolymerization of waste poly(ethylene terephthalate) (PETW) flakes from bottles was investigated using a nonaqueous NaOH in ethylene glycol solution and was carried out at p(atm) from 150 to 185 degrees C, using a NaOH: PET molar ratio of 4:1. The increasing amount of water taken up by the flakes and after submitting them to thermopressing at 260 degrees C increased the reactivity of the rectangular specimens thermopressed during the depolymerization. At a stirring rate value of 1360 rpm, the product was removed from the unreacted PET surface and the chemical reaction was rate-determining. Using the kinetic model of shrinking core of heterogeneous chemical reaction control, considering the formation and growth of cracks and pores on the polymer surface, the E-a value was 172.7 kJ(.)mol(-1), which was relatively high. However, in the thermodynamic analysis it was shown that the compensation effect of the Delta S-double dagger over the Delta H-double dagger is sufficiently high to compensate for the high Ea.