An attempt was made to prepare ultrafine titanium dioxide (TiO2) particles in the nanometer range by making use of the hydrolysis and condensation reactions of tetraisopropylorthotitanate (TTIP) in the inner aqueous phase of Aerosol OT reversed micelles formed in cyclohexane. Addition of linear alcohols (C-2 to C-6) to TTIP was found to affect the size of the titanium dioxide particles formed. The particle size was strongly dependent on the alkyl chain length and the amount of the alcohols. Addition of alcohols with the alkyl chain length smaller than 1-butanol increased the size of the particles over that prepared without alcohol addition, while addition of alcohols with a moderately long alkyl chain, like 1-pentanol and 1-hexanol, caused a decrease in the particle size. In particular, addition of 1-hexanol was found to yield TiO2 particles with a best dispersibility and sizes of around 10 nm.