Keratin-poly(vinyl alcohol) (PVA) blend fibers containing 13-46 wt % of -SSO3-Na+ (S-sulfo) keratin were prepared by the wet-spinning technique. They were formed by dehydration of an aqueous solution of S-sulfo keratin and PVA (spinning dope) in a coagulation bath of sodium sulfate-saturated solution and subsequently drawn. Keratin-PVA fibers showed higher tenacity than that of wool, presumably originating from the high mechanical strength of the PVA component. The heat treatment at about 200degreesC improved the waterproof characteristics such as shrinkage of keratin-PVA fibers more conspicuously than did PVA fibers. That is, after heat treatment at 195degreesC for 10 min, keratin-PVA blend fiber shrank 20% in water at 60degreesC, whereas PVA fiber shrank 56%. Differential thermal analysis suggested the crosslinking of disulfide bonds between keratin molecules during the heat treatment, whereas the additional crystallization of PVA component was not observed. Adsorption of heavy metal and toxic gas to keratin-PVA fibers was also investigated. Keratin-PVA fiber was found to adsorb Ag+ and formaldehyde gas more efficiently than PVA. Thus, blends of keratin and PVA were advantageous for both polymer fibers. (C) 2003 Wiley Periodicals, Inc.