TiO2 single crystals have been studied in aqueous electrolyte with in situ FTIR, in which the probe ir beam and a beam of uv/vis light are coincident on the crystal surface. It is shown that both photo-induced evolution of oxygen from water and the oxidation of model organics can be followed with this technique and, in particular, the detailed behaviour of the surface-bound oxygen and carbon dioxide can be followed. Evidence is also presented for the reconstruction of the TiO2 (001) surface following extended exposure to ambient conditions and re-etching. This reconstruction is found to have a profound effect on the selectivity of the surface to the oxidation of organic species.