The fracture energy of ti/Al2O3 composite interfaces has been determined by four point bending tests of sandwich specimens for different thicknesses of metal interlayers at 900°C. The interfacial fracture was found to be brittle. An intermetallic reaction product (Ti3Al) was produced at the interface after the diffusion bonding process. When the metal interlayer is thicker, there is more plastic energy dissipation in the metal during the fracture process. Therefore, the interfacial fracture energy increases. This can be seen from the fact that there is a larger plastic zone size with increasing thickness of the metal interlayer. The measured interfacial fracture energy TI/Al2O3 ranges form 9.6 J/m2 to 45.1 J/m2. The intrinsic interfacial fracture energy is obtained to be 0.26 J/m2. The embrittlement of the interface after the diffusion bonding process causes this value to be smaller than work of adhesion for Ti/Al2O3 (2.0 J/m2).