Bicomponent fibers were wet-spun from soybean protein and poly(vinyl alcohol). The protein core of the spun bicomponent fiber was brittle and showed a high frequency of core breakage upon drawing. Our effort was then to study the soybean protein solution, with the aim of trying to understand the cause for fiber brittleness and to determine the optimum solution conditions for fiber spinning. The effects of alkali, urea, and sodium sulfite on the viscosity of the soybean protein solution were examined. The hydrolytic stability of the soybean protein solution was examined at various pH values at two temperatures (room temperature and 60 degrees C). Both the viscosity and gel electrophoresis were used for this purpose. The degradation of the soybean protein and the existing microgels in the protein spinning solution were thought to be the causes for the poor fiber drawability. Extent of protein denaturation will also effect the fiber drawability.