PURPOSE: A titanium alkoxide is dissolved in an aqueous hydrogen peroxide and treated with reduced pressure to covert the alkoxy groups in the alkoxide into a volatile organic compound and remove it whereby an aqueous solution of titanium hydroperoxide of high purity is readily obtained.

CONSTITUTION: A titanium alkoxide such as titanium methoxide or ethoxide is dissolved in an aqueous hydrogen peroxide under cooling with ice water. Then, the aqueous solution is subjected to vacuum-distillation to remove the alcohol liberated by substitution with hydrogen peroxide and a small amount of the oxidation products of the alcohol such as ketone or aldehyde whereby an aqueous solution of titanium hydroperoxide of high purity is obtained. The aqueous solution is suitably used for making titanium dioxide powder, film or fiber of high purity.