A blue-emitting phosphor of titanium-doped zinc spinel (ZnAl2O4:Ti; Ti=0–6.0mol% in relation to Al) nanopowders was prepared by a simple sol–gel method. On annealing at 1000°C, single-phase ZnAl2O4:Ti powders had primary particles of 25–30nm in size and most Ti ions in the form of Ti4+. Under UV excitation at 280nm, a strong and broad blue emission centered at 435nm was observed. The sources of the excitation and emission were assigned to the charge-transfer excitation and recombination between O2––Ti4+ and Ti3+–O– ion pairs. Optimum brightness occurred at a doping of 2.0mol% Ti. The decay lifetime of ZnAl2O4:2%Ti was calculated to be 3.0ms for the blue emission with CIE coordinates of x=0.168 and y=0.153. The results suggest that ZnAl2O4:Ti is a promising candidate for application as a blue component phosphor for UV-converting white light-emitting diodes.