Process for producing lightproof titanium dioxide pigment

In a process for producing a substantially lightproof titanium dioxide pigment suitable for matting artificial fibers, in which a water soluble vanadium compound which is a vanadate or vanadyl salt is added to an aqueous suspension of the titanium dioxide pigment to form a precipitate of a vanadium hydroxide in the amount of 0.01-0.5 percent of the weight of the pigment calculated as V.sub.2 O.sub.5 on the surface of the titanium dioxide particles, whereafter the suspension is filtered, washed, and the washed precipitate is thermally dried, and ground, the improvement comprising adding to said aqueous suspension an aluminum compound, which is an aluminate or aluminum salt so as to cause a precipitate of a vanadium hydroxide and an aluminum hydroxide on said titanium dioxide particles, the amount of said aluminum hydroxide being 0.5-5 percent of the weight of the pigment calculated as Al.sub.2 O.sub.3 and effecting the thermal drying and the grinding at such a low temperature that the pigment temperature is between 105.degree.C and 300.degree.C and for such a short period that the vanadium hydroxide remains on the surface of the titanium dioxide pigment particles without being calcinated into the particles.