Electron emission characteristics of needle-shaped titanium dioxide (TiO2) cathodes fabricated by a printing method and the change in current densities before and after ultraviolet (UV) light irradiation were investigated. A field enhanced surface treatment by applying a high electric field to the printed TiO2 cathodes was found to be effective for improvement in field emission, resulting in protrusion of TiO2 nanorods from the cathode surface and field emission at and above 2.5 V/mu m with a current density of about 1 mA/cm(2) at 8 V/mu m. The emission current density of TiO2 cathodes can be increased by UV light irradiation with gradual increase and decrease from and to the initial level with and without UV light. (C) 2009 American Vacuum Society. [DOI: 10.1116/1.3070652]