Mullite-based ceramics prepared from a mixture of kaolin and alumina were plastically deformed in uniaxial compression tests at high strain rates (<(epsilon)over bar> = 10(-2)-10(-3) s-(1)) at 1450 degrees and 1500 degrees C, Deformation occurred with barreling in tests that used SiC platens coated with h-BN, This study shows that more-suitable lubricants and molds (platens) must be found, to reduce friction between the mullite-based ceramics and molds. However, this hot-working method can be used to give a fine, textured surface to mullite-based ceramic substrates for poly-crystalline silicon thin-film solar cells.