The flammability behavior of a blend fabric cannot be predicted from the flammability characteristics of its component fibers because of the physical or chemical interaction of the thermal degradation products of the blend during heating or combustion. In order to consider the design of flame retardant fabrics from blends of cotton as a flammable fiber and novoloid fiber as a nonflammable and heat-resistant fiber, the thermal degradation of each fiber and blend of fibers were studied using a conventional dynamic thermogravimetric technique in a flowing air atmosphere at several heating rates. Quantitative data are presented which pinpoint how the thermal degradation behavior of this blend differs from that of the components. Comparison of the thermogravimetric curves and calculated kinetic parameters indicates that interactions occur faintly between the novoloid and cotton components in the blends. The thermogravimetric analysis data show two degradation stages in air atmosphere.