A process for producing acidic boratozirconium chloride sols which comprises: reacting a zirconium compound with a boron compound in molar ratios of B/Zr of 0.3-1.2 together with a compound of a metal M, the metal M being selected from the group consisting of divalent, trivalent, tetravalent and pentavalent metals in molar ratios of M/Zr of about 0.01-1 in water in the presence of chloride ions in molar ratios of Cl/Zr of not less than about 1.The acidic boratozirconium chloride sol may be converted to basic boratozirconium sols by reacting the acidic sol with a basic carbonate compound such as ammonium carbonate.The sols, either acidic or basic, are readily gelled by contact with a dehydration solvent such as methanol or actone.The gel is calcined at relatively low temperatures to provide zirconia which is either very pure or stabilized in varied degrees.