Polycrystalline, stoichiometric β- silicon carbide fiber tow suitable for ceramic or metallic matrix composite use has been prepared using a polymer precursor route to obtain textile grade, weavable fibers. Individual filaments have a diameter of 10 μm, an average tensile strength of up to 3.4 GPa (500 ksi), an elastic modulus up to 430 GPa (62 msi) and a density > 3.1 g/cm3. Crystallites average about 60 nm by x-ray line broadening. The SiC fiber shows improved mechanical and thermal stability properties, especially in an inert atmosphere, as compared to commercial polymer-derived SiC ceramic fibers. Thermochemical and mechanical properties, as well as fractography and microstructure will be presented.