As part of SRRC's ongoing research program on reduction of byssinogenic activity of cotton fiber/dust, the effect of temperatures >200°C on heat-labile endotoxins has been evaluated. Our previous reports at Cotton Dust Research Conferences described detoxification of cotton fiber using heated metal plates at 212 or 219C or a forced draft oven at 235 or 250°C. The current heat source, a pilot plant dryer run at 233, 246, or 260°C, will be compared to the plates and oven for effect on endotoxin reduction and fiber properties, including strength and color. The results of heat treatment of cotton fiber will be related to the results of heat detoxification of lipopolysaccharide (endotoxin) at 200-260°C.