Undoped and Sb-doped ZnO nanoparticles were successfully synthesized by vapor condensation method from pure Zn and Zn-Sb alloy with different mole ratios (50:1, 15:1 and 6:1) as raw materials in a flowing gas mixture of Ar+O-2. The morphological characteristics, phase structure, composition and chemical state of nanoparticles were measured by TEM, HRTEM, XRD, EDX and XPS, respectively. The microstructures of thick films based on nanoparticles were investigated by SEM. The gas sensitivity of thick film based on Sb-doped ZnO nanoparticles to volatile organic compounds (VOCs), benzene, toluene, xylene, acetone and alcohol, as a function of temperature were measured, and compared to undoped ZnO thick film. After doping with Sb, the morphology of ZnO nanoparticles is modified from the needle-shape to the polygon; the gas sensitivity of the thick films is greatly improved, wherein the sensitivity of Sb-doped ZnO nanoparticles produced from alloy with Zn/Sb = 15:1 is maximal and response-recovery time is short. The gas sensitivity of the ZnO-based nanoparticles maybe depended on the content and chemical state of Sb in the ZnO lattices. (C) 2004 Elsevier B.V. All rights reserved.