Nanocrystalline titanium dioxides (TiO 2 ) prepared from (a) titanium tetrachloride (TiCl 4 ) and (b) titanium tetraisopropoxide (TTIP) have been compared. The effect of the reaction parameters on the phase formation of TiO 2 was investigated systematically. For TiO 2 prepared by hydrolysis of TiCl 4 , the crystal phase changed with the speed of TiCl 4 addition and slow addition favoured the formation of rutile. For TiO 2 prepared by hydrolysis of Ti(OC 3 H 7 ) 4 , the reduction in hydrolysis rate associated with lower reaction temperatures promoted rutile formation. For both TiCl 4 and TTIP derived samples, increasing the anatase content decreased the measured rate of photocatalytic oxidation of isopropanol to acetone.