Mononuclear titanium oxide species in faujasites of different Si/Al ratios are prepared by reaction of dehydrated zeolites with TiCl4 at 100 degrees C. The analysis of UV-vis diffuse reflectance spectra in combination with Raman spectroscopy and X-ray diffraction reveals the presence of three different types of titanium oxide species in the faujasite structure exhibiting excitation energies for the charge transfer from the 2p orbitals of oxygen ligands to the 3d orbitals of Ti of around 36 000, 45 000 and 49 000 cm(-1). A reliable evaluation of diffuse reflectance spectra requires the calculation of the Kubelka-Munk spectra from the absolute reflectance of the sample. The different titanium oxide types are proposed to result from monofunctional, bifunctional, and multifunctional bonding of TiCl4 to isolated or neighboring OH groups or to hydroxyl nests with coordination numbers ranging from four to six. The blue shifts in the UV-vis spectra of mononuclear titanium oxide species can be discriminated from those of quantum-sized titania particles.