The work described in this thesis was carried out in the context of the EU-7th Framework Programme for Research and Technological Development within the REFINE project. The aim was to develop new skills and expertise in sustainable green materials manufacturing and technologies and applications for the development of a greener and more sustainable society. This project was based on the unique combination of knowledge along the production chain in polymer and materials science, biotechnology and applications, ecological impact and Life Cycle Analysis. Following the given tasks, the individual focus of this thesis was on hydrolytic enzymes as green catalysts with an enormous unexploited potential for the synthesis, hydrolysis and functionalization of polyesters. In a first step, the biocatalyzed synthesis of polyesters was studied. In this context we investigated the synthetic potential of Thermobifida cellulosilytica cutinase 1 (Thc_cut1), an hydrolytic enzyme previously reported for the hydrolysis of poly(ethylene terephthalate). Production, purification and immobilization of the biocatalyst together with the synthesis of aliphatic bio-based polyesters with Mw of around 1900 and Mn of around 1000 Da was investigated and compared to lipase B from Candida antarctica (CaLB) or cutinase from Humicola insolens (HiC). Computational studies were also carried out for a better comparison of these biocatalysts. Additionally, the use of a commercial preparation of CaLB for the synthesis of aliphatic-aromatic oligoesters in a simple one-step, one-pot reaction system was described. A detailed analysis of the reaction products showed that the best combination of diester and polyol was consisting of dimethyl isophthalate with 1,10-decanediol that led to a Mw as high as 1512 Da and a conversion of 87% after 96 h of reaction. In a second instance, biocatalysts were investigated for their ability to hydrolyze and functionalize chemically-produced bio-based polyesters. HiC was explored for the surface hydrolysis of poly(L-lactic acid) (PLA) films. A change of water contact angle from 74.6 to 33.1 was measured while the roughness and waviness were an order of magnitude higher in comparison to the blank. Surface functionalization was demonstrated using two different techniques, 14C-radiochemical analysis and X-ray photoelectron spectroscopy using 14C-butyric acid sodium salt and 4,4,4-trifluorobutyric acid as model molecules, respectively. Moreover, the enzymatic hydrolysis of poly(ethylene furanoate) (PEF) was also successfully carried out. PEF powders of various molecular weights (6, 10 and 40 kDa) were synthetized and their susceptibility to enzymatic hydrolysis was investigated for the first time. According to LC/TOF-MS analysis, Thc_cut1 liberated both 2,5-furandicarboxylic acid and oligomers of up to DP4 for all the tested samples. Hence, in summary in this work the high potential of environmentally friendly biocatalysts both for production and processing of polymers was demonstrated.