Nitrogen-doped ZnO nanocrystallites with primary diameter in the range of 30-50 nm were synthesized rapidly by self-assembly combustion technique using urea and citric acid as fuels, zinc nitrate as oxidant. The variation of adiabatic. ame temperature with the various fuel compounds was calculated theoretically according to the thermodynamic concept. XRD, SEM and XPS were used to characterize the as-synthesized products. The anti-ultraviolet and anti-bacterium ability of the products were estimated by testing the UPF index and repressing-bacterium circle diameter of the cotton fabrics, which were treated using the as-synthesized products. The results show that a small quantity of citric acid has excellent coordinated action with urea and accelerates the nitrogen doping reaction course, obtaining perfect nitrogen-doped ZnO nanocrystallites with uniform color and particles size. The analysis of XPS spectrum shows that the nitrogen incorporation produces an N-O bonding region. The incorporation of nitrogen greatly improves the anti-ultraviolet and anti-bacterium properties of ZnO nanocrystallites, which can be attributed to the change of surface properties of nitrogen-doped ZnO, such as O vacancies and crystal deficiency. (C) 2008 Elsevier B.V. All rights reserved.