Calcium alginate yarn (30 fibers) and calcium alginate nanocomposite yarn (30 fibers) containing 0.05-2.00% w/w chitin whiskers were both prepared by wet spinning process. The whiskers were prepared by acid hydrolysis of chitin from shrimp shells. The average length and width of the whiskers were 343 and 46 nm, with the aspect ratio being similar to 7.5. Incorporation of a low amount of the whiskers in the nanocomposite fibers improved both the mechanical and the thermal properties of the fibers significantly, possibly a result of the specific interactions, i.e., hydrogen bonding and electrostatic interactions, between the alginate molecules and the homogeneously dispersed chitin whiskers. Biodegradation of the calcium alginate fibers and the nanocomposite fibers was tested in Tris-HCl buffer solution and the same buffer solution that contained lysozyme. The addition of the chitin whiskers in the nanocomposites fibers accelerated the biodegradation process of the fibers in the presence of lysozyme, whereas the presence of Ca2+ ions in the Tris-HCl buffer solution helped to improve the tenacity of both the alginate and the nanocomposite fibers. (c) 2008 Wiley Periodicals, Inc.