Calcium phosphate (CP) in aqueous solution was exposed to thin-film TiO2 surfaces at predetermined times ranging from 10 min to 20 h using a liquid reaction apparatus (LRA). Surface analysis was then performed using X-ray photoelectron (XPS) and Auger electron (AES) spectroscopies and time-of-flight secondary ion mass spectrometry (ToF-SIMS) with polyatomic primary ions. XPS revealed that CP nucleated and grew on the TiO2 surface, with phosphate groups growing on top of an initial 2-dimensional (2D) Ca-rich layer. AES depth profiling of a 4-h solution exposure complemented this finding and gave additional evidence for 3-dimensional (3D) phosphate islands forming on top of the calcium. ToF-SIMS analysis of CP adsorbed on the surface indicated that the predominant phase on the surface was brushite, CaHPO4. 2H(2)O. A model for Ca2+ cation bridging at the oxide interface is proposed.