Experimental investigation has been undertaken with the goal to determine the effect of specific surface area, extent of hydroxylation, surface acidity properties on TiO₂ photocatalytic activity in deep oxidation of gas phase acetone. pH of aging, calcination temperature and calcination time were varied in TiO₂ preparation using TiCl₄ hydrolysis. The photocatalytic activity attains its maximal values at aging pH close to 4 and calcination temperature different for different calcination time and hydrolysis conditions. Specific surface area continuously decreases with an increase in calcination temperature. Maximal photocatalytic activity corresponds to very different surface area for different series of TiO₂ samples. These data mean that TiO₂ particles size and surface area does not have a direct influence on photocatalytic activity but it is rather surface properties such as surface acidity and hydroxyl groups content, which are different for samples prepared at different pH and calcination temperature, that determine the photocatalytic activity.