A novel phenolic resin/silica hybrid ceramer fabricated via the sol-gel method was prepared. Hybrid systems with different inorganic contents were used as the matrix precursors to fabricate the silica containing carbon/carbon composites. Isothermal oxidation tests at temperatures ranging between 650 degreesC and 750 degreesC were employed to investigate how the oxidation resistance of the derived carbon/carbon composites is improved. Furthermore, the isothermal oxidation test results between 550 degreesC and 615 degreesC were used to calculate the activation energy of oxidation. Experimental results demonstrate that the silica containing carbon/carbon composites have a better oxidation resistance than those derived from pure phenolic resins. Meanwhile, morphological observations indicate that the oxidation of carbon fibers is retarded in the phenolic resin/silica hybrid derived carbon/carbon composites.