An aqueous titanium oxide-dispersed sol comprising titanium oxide particles
dispersed in water, said sol comprising chloride ions in an amount of 50
to 10,000 ppm by weight as the chlorine element. Titanium tetrachloride is
hydrolyzed to form an aqueous titanium oxide-dispersed sol and the
chloride ion concentration thereof is controlled. Another aqueous titanium
oxide-dispersed sol comprising brookite-type titanium oxide particles
dispersed in water, said titanium oxide particles having an average
particle size of not more than 0.5 .mu.m and a specific surface area of
not less than 20 m.sup.2 /g. Addition of titanium tetrachloride to hot
water at 75 to 100.degree. C. followed by hydrolysis at 75.degree. C. to
the boiling point of the mixture.
