By applying fumed SiO2 as support material, introducing the additive of polyethylene glycol (PEG) in the preparation medium and a deposition-precipitation method based on organic phase, we prepared the novel fumed SiO2-supported VPO catalysts. The catalysts are the most selective in comparison to the various supported VPO counterparts for the partial oxidation of n-butane to maleic anhydride. At 653 K the derived samples showed butane conversion of 33-40% and MA selectivity of 87-65 mol%. The catalysts not only showed good performance at lower reaction temperatures, but also maintained higher MA selectivity at different loadings. In addition to the unique nature of fumed SiO2, the highly uniform dispersion of VPO component and the involved VPO-support interaction, co-existence of predominant (VO)(2)P2O7 phase and minor VOPO4 may also be beneficial to the good performance on the unique fumed SiO2-based catalysts. In addition, broadening of the (2 0 0) diffraction line of (VO)(2)P2O7 phase is an indication of structural disorder, one considered to be relevant to MA formation. (C) 2004 Elsevier B.V. All rights reserved.