Well-aligned TiO(2)/Ti nanotube arrays were fabricated by anodic oxidation, then carbon nanotubes (CNTs) were grown into TiO(2)/Ti nanotube arrays to form CNTs/TiO(2)/Ti composite nanostructures by catalytic chemical-vapor deposition for different deposition times. The morphology and quality of samples were assessed by field-emission scanning-electron microscopy and Raman spectroscopy. The field emission (FE) results indicate that the FE properties of CNTs/TiO(2)/Ti composite nanostructures were dramatically improved compared with bare TiO(2)/Ti nanotube arrays, and when the growth time of CNTs was 60 min, the composite nanostructures possessed the lowest turn-on field of 1.3 V/mu m, the highest emission-current density of 10 mA/cm(2) was easily gained at 5.6 V/mu m, and there was good FE stability. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3516017]