Insulation materials suited to high temperature applications, such as the insulation of furnaces, are formed from a mixture of pitch carbon fibers, such as isotropic pitch carbon fibers, and a binder comprising a solution of sugar in water. The sugar solution is preferably at a concentration of from 20 60% sucrose to yield a low density material having high flexural strength and low thermal conductivity when carbonized to a temperature of about 1800.degree. C.