Materials in the form of highly dispersed 12-phosphotungstic acid (PWA) in mesoporous SiO2 framework (PWA/meso-SiO2) have been synthesized by one-step condensation method. The samples were characterized by XRD, TEM, EDX, FE-SEM, FT-IR, P-31 MAS NMR and N-2 adsorption. The mesostructure of the materials obtained can be maintained up to the PWA loading amount of 30 wt%. The specific surface area and the pore size of the PWA/meso-SiO2 are 600 m(2) g(-1) and 8.9 nm, respectively, for 30 wt% PWA loading. PWA clusters preserved their Keggin ion structure and exist in the SiO2 framework with partial interactions between PWA and SiO2. (C) 2004 Kluwer Academic Publishers.