Reaction between Ti metal and B2O3 is investigated using x-ray photoelectron spectroscopy, scanning electron microscopy and wavelength dispersive spectrometry mapping techniques because titanium-to-borate glass seals have great potential for use in biomedical and aerospace applications. Immediately after the deposition of a 3 nm thick titanium film under UHV conditions on in situ fractured B2O3 at room temperature, TiBx, Ti–O–B and Ti–O–Ti linkages are formed. The following initial reaction occurs at the Ti–B2O3 interface Ti+xB2O3 rarr TiB2x–2+B2O3–y+½(y+3x–3)O2 in situ heating of the film leads to the incorporation of released oxygen in both the product TiBx layer and the titanium film. TiBx precipitates are formed on the titanium side of diffusion couples prepared at 1000°C. The implications of these results for glass-to-metal adherence are discussed.