Niobium- or vanadium-doped anatase sols were prepared by hydrothermal treatment of 0.1 mol/dm(3) peroxotitanium complex aqueous solutions dissolving 0-10 mol% niobium or vanadium at 100degreesC for 8 h. Niobium-doping caused the increase of lattice constants of anatase and the shape change of anatase crystal from spindle-like to cubic-like structure, but no change of the optical absorbance. Vanadium-doping caused the decrease of lattice constant of c-axis, the miniaturization of anatase crystal and the increase of optical absorbance at the wavelength from 350-700 nm.