Nanoparticles of indium oxide, tin oxide and indium oxide doped with tin oxide (ITO) have been prepared by Chemical Vapor Synthesis, CVS (a modified CVD process), starting with In- (tmhd)3 as precursor. A modification of the CVS process using a novel radio-frequency reaction zone has been developed in order to avoid the rapid decomposition of the nanocrystalline indium oxide particles at high temperatures. These oxides are candidates for applications as transparent conducting oxides, catalysts and gas sensors. Structural characterization by high resolution scanning and transmission electron microscopy and X-ray-diffraction has been used to determine the phase, grain size, grain size distribution and crystallinity of the nanoparticles. The specific surface area, and particle or agglomerate size of the powders have been measured by nitrogen sorption. Agglomerate sizes in aqueous dispersions have been determined by photon correlation spectroscopy. Zeta-potentials were measured. As well CVS powders exhibit a narrow size distribution with an average size of about 5 nm.