Synthetic aromatic polyesters such as polyethylene terephthalate (PET) are degraded by microbial polyester hydrolases at mild reaction conditions compared to chemical processes. PET films were hydrolyzed by the polyester hydrolase TfCut2 from Thermobifida fusca KW3 in an aqueous reaction system contained in an ultrafiltration membrane reactor The continuous removal of inhibitory hydrolysis products by the ultrafiltration membrane increased the efficiency of the biocatalytic hydrolysis of PET by 70% over a reaction time of 24 h compared to a hydrolysis performed in batch mode. A model describing the biocatalytic hydrolysis of PET films with simultaneous ultrafiltration to remove the reaction products was in good agreement with the experimental data obtained. The ionic strength of the buffer as well as the mechanical agitation of the reaction mixture markedly influenced the enzymatic PET hydrolysis rates. (C) 2015 Elsevier B.V. All rights reserved