In this study, alpha-amylase was covalently immobilized on modified polyimide materials. Polyimide (PI) was prepared with pyromellitic dianhydride (PMDA) and 4,4'-oxydianline (4,4'-ODA) in the solution of N,N-dimethylformamide (DMF). Free amine groups on the surface of the polyimide membranes were generated by the amination reaction of polyimides with hexamethylenediamine (HMDA). Surface-aminated membranes were then subjected to enzyme immobilization. The morphology of the polymeric support was characterized by scanning electron microscopy (SEM). Chemical structure of PMDA-ODA PI membranes was characterized by FTIR. SEM and FTIR results showed that the enzyme was successfully covalently attached to the polymeric support. Immobilization efficiency and enzyme activity of alpha-amylase was examined at various pH values (3.0 - 8.0) and temperatures (15 - 80 degrees C). Immobilization yield was found to be 285.45 mg per gram for the modified polyimide films. Enzyme assays demonstrated that the immobilized enzyme exhibited better thermo-stability than the free one.