The application of ultrasound was found to enhance enzymatic hydrolysis of poly(ethylene terephthalate) (PET). After a short activation phase up to 6.6 times increase in the amount of released products was found. PET powder with lower crystallinity of 8% was hydrolyzed faster when compared to PET with 28% crystallinity. Ultrasound activation was found to be around three times more effective on powders vs. films most likely due to a larger surface area accessible to the enzyme. (C) 2016 Elsevier Ltd. All rights reserved.