One of the key aspects of the diffusion bonding technology is the adhesion at the interface, to whom most of the mechanical properties can be ascribed. Titanium has been largely used in diffusion bonding involving aluminium oxide, as it reacts with the ceramic promoting adhesion. The present work attends to the interface formation between Al2O3 and titanium, during diffusion bonding experiments performed under vacuum. It is verified, by SEM microstructure characterisation, EDS microanalysis, X-ray diffraction and microhardness measurements, that the adhesion occurred by the ceramic dissolution, in presence of titanium, in elementary aluminium and oxygen atoms, followed by the oxygen diffusion into the titanium. The aluminium accumulation at the interface is favourable to the Ti3Al formation observed.