Nanoparticles of A1-doped SnO2 have been hydrothermally synthesized. The influences of the hydrothermal reaction time, the molar ratio of Sn/A1 as well as the pH value of the solution have been studied. During the hydrothermal synthesis, the particle's core is rich in Sn and the surface is rich in A1. The A1-rich surface prevents the particles from further growing up either in the hydrothermal condition or during the calcination at 600 degreesC for a short period of time. The optimal hydrothermal synthesis condition of the nanoparticles is pH 5, Sn/A1 = 4:1 and 12 It at 160degreesC. The products have been studied by XRD, TEM and (27)A1 solid-state NMR. (C) 2004 Elsevier B.V. All rights reserved.