The field emission (FE) properties of ZnO and NiO-coated ZnO (NiO/ZnO) nanorods are investigated under vacuum of 7x10(-7) Torr and oxygen rich vacuum of 1x10(-5) Torr. The ZnO nanorods were synthesized on a Si(100) substrate by metal-organic chemical vapor deposition, and the NiO film with the thickness of similar to 15 nm was coated by using atomic layer deposition. The turn-on voltages of the NiO/ZnO nanorod and the ZnO nanorod were similar to 5.2 and similar to 3.0 V/mu m at 1 mu A/cm(2), respectively. The electron FE stability of the NiO/ZnO nanorods to the ZnO nanorod was significantly improved in oxygen rich vacuum even. (C) 2008 American Vacuum Society.