Nanoscale TiO2 thin films were prepared by pulsed laser deposition (PLD) technique on Indium Tin Oxide (ITO) surfaces. TiO2 thin films were deposited as a function of oxygen pressure and substrate temperature. Results from X-ray photoelectron spectroscopy (XPS) show a 0.6 eV shift in binding energy of Ti 2p3/2 with variation on oxygen partial pressure. Based on linear scan voltammetry (LSV), we found that the onset potential of TiOx thin films increased in absolute energy scale by a magnitude of 0.2 to 0.8 eV when deposition temperature decreased from 873 to 298 K. This implies that the flatband potential as well as the Fermi energy of the TiO2 thin film vary with the concentration of oxygen vacancies. Rutile weight fraction ranged from unity to near zero was observed, depending on experimental condition. In photoelectrochemical study, the best incident photon conversion efficiency (IPCE) was observed at deposition temperature of 873K which yielded 2.5 to 5 % of IPCE(l=320nm). The differences were attributed to the variation in degree of crystallization and phase composition of TiO2. Our results suggest that the photocatalytic reactivity of TiO2 thin film can be optimized depending on the desired redox reaction and this can be achieved by moderately manipulating oxygen pressure and substrate temperature since these two parameters greatly impact the oxygen vacancy concentration in the TiOx thin film deposited in PLD. This, in turn, affects the position of the flatband potential and its photocatalytic reactivity.