The immobilization of lipases is often used in biotechnology to improve the performance, reusability, and stability of the enzyme.Candida antarcticalipase B (Cal-B) has been used as a catalyst in trans-esterification reaction. To improve the utilization of Cal-B, therefore the immobilization of Cal-B onto a polymer matrix became crucial. In this study, polyethersulfone (PES) and sulfonated polyethersulfone (SPES) membranes were used as matrices of Cal-B immobilization. SPES was previously synthesized by modifying PES using chlorosulfonic acid (ClSO3H) to improve the immobilization of Cal-B. SPES-PSf (polysulfone) blended membranes were also successfully prepared by blending SPES, PSf, and PEG inN-methylpyrrolidone (NMP) as the solvent using phase-inversion method. The attenuated total reflectance (ATR)-FTIR spectrum showed characteristic peaks of the immobilized Cal-B on the matrix at peak 3184.03 cm(-1)(-N-H bonds) and 1683.49 cm(-1)(-CH deformation bonds). The Raman spectroscopy of the PES-based membranes before and after sulfonation reaction showed the deviations from the symmetrical structure of PES, with specific Raman shifts at 784.11 cm(-1), 1150.95 cm(-1), and 1588.9 cm(-1). Cal-B was successfully immobilized and loaded onto SPES membrane. By Lowry assay, it was detected that 140.3 mu g/cm(2)enzyme was successfully loaded into the 17.3 cm(2)of membrane. The value was one and a half times higher than PES (91.0 mu g/cm(2)in 17.3 cm(2)). However, the hydrolytic activity of Cal-B immobilized onto SPES membrane (17.0p-NP/min/cm(2)) was five times lower than Cal-B immobilized onto PES membrane (80.4p-NP/min/cm(2)).