Hydroxypropyl chitosan (HPCS) was synthesized from chitosan and propylene oxide under alkali conditions. It was characterized by IR spectroscopy and X-ray diffraction (XRD). We prepared alginate/HPCS blend fibers by spinning their solution through a viscose-type spinneret into a coagulating bath containing aqueous CaCl2 and ethanol. The structure and properties of the blend fibers were studied with the aid of IR spectroscopy, scanning electron microscopy, and XRD. The results indicate a good miscibility between alginate and HPCS because of the strong interaction of the intermolecular hydrogen bonds. The mechanical properties and water-retention properties were also measured. The best values of the tensile strength and breaking elongation of the blend fibers were obtained when the HPCS content was 30 wt %. The water-retention values of the blend fibers increased as the amount of HPCS increased. Antibacterial fibers, obtained by the treatment of the fibers with an aqueous solution of silver nitrate, exhibited good antibacterial activity to Staphylococcus aureus. (c) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012