Novel chitosan/cellulose acetate blend hollow fibers were prepared by the wet spinning method to obtain adsorptive membranes. In the hollow fiber membranes, cellulose acetate (CA) acted as a matrix polymer and chitosan (CS) as a functional polymer to provide the membrane with coupling or reactive sites for affinity-based separations. Formic acid was used as the co-solvent for both CA and CS to prepare the dope solution and NaOH solution was used as the external and internal coagulants in the wet spinning fabrication process. The mixability and possible interactions between CA and CS in the blend hollow fibers were investigated through FTIR and XRD analyses. FTIR spectroscopy revealed that the blending of CS with CA involved some chemical interactions. XRD results showed a single peak for CS and CA blend hollow fibers, similar to the one for CA, suggesting that good mixability was achieved between the two polymers. The properties of the blend hollow fibers were characterized through water flux measurements, surface and cross-section examinations and adsorption performances to copper ions and bovine serum albumin (BSA) on the surfaces, and were compared with those for CA hollow fibers. SEM image clearly showed the sponge-like and macrovoids-free porous structures of the hollow fibers. The blend hollow fibers displayed good tensile stress even though the tensile stress reduced with the increase of the CS content in the blend. The blend hollow fibers achieved significantly better adsorption performance as compared to that of CA hollow fibers, indicating the benefit in adding CS into CA to make novel blend hollow fibers in improving the performance of the traditional CA hollow fibers, especially for the affinity-based separation applications. (c) 2005 Elsevier B.V. All rights reserved.