The paper explored the catalytic activity of a cell debris self-immobilized thermophilic lipase for polyester synthesis, using the ring-opening polymerization of epsilon-caprolactone as model. Effects of biocatalyst concentration, temperature, and reaction medium on monomer conversion and product molecular weight were systematically evaluated. The biocatalyst displayed high catalytic activity at high temperatures (70-90 A degrees C), with 100 % monomer conversion. High monomer conversion values (> 90 %) were achieved in both hydrophobic and hydrophilic solvents, and also in solvent-free system, with the exception of dichloromethane. Poly(epsilon-caprolactone) was obtained in 100 % monomer conversion, with a number-average molecular weight of 1,680 g/mol and a polydispersity index of 1.35 in cyclohexane at 70 A degrees C for 72 h. Furthermore, the biocatalyst exhibited excellent operational stability, with monomer conversion values exceeding 90 % over the course of 15 batch reactions.