Controlled and thorough stabilization of pitch is provided by incorporating an oxidant into the pitch. In one embodiment of the invention, the oxidant is intimately mixed with the pitch. In another embodiment, the oxidant is encapsulated in a suitable encapsulant and the encapsulated oxidant is intimately mixed with the pitch. This material is particularly useful in the preparation of a carbon-carbon composite, but is also useful for preparing fibers and solid preforms.