A high temperature compressed non-asbestos sheet is provided which is effective for gasketing applications in temperatures up to at least 900. degree. F. The sheet is formed from carbon fibers having a high percentage of carbonization and a low modulus of elasticity. The carbon content of the fibers is above 90% while the modulus of elasticity is less than 10,000,000 psi. , and such fibers form at least 75% of the fiber content of the sheet. The carbon fibers may be blended with small portions of organic fibers to enhance the physical properties of the sheet.