Titanium sulfate supported on $TiO_2$was prepared by impregnation of powdered $TiO_2$with an aqueous solution of titanium sulfate followed by calcining in air at high temperature. For Ti$(SO_4)_2/TiO_2$ samples calcined at 300 $^{circ}C$, no diffraction lines of titanium sulfate are observed at $Ti(SO_4)_2$loading up to 30 wt%, indicating good dispersion of $Ti(SO_4)_2$ on the surface of $TiO_2$. The acidity of the catalysts increased in proportion to the titanium sulfate content up to 20 wt% of $Ti(SO_4)_2$. 20 wt% $Ti(SO_4)_2/TiO_2$ calcined at 300 $^{circ}C$ exhibited maximum catalytic activities for 2-propanol dehydration and cumene dealkylation. The catalytic activities for these reactions, were correlated with the acidity of catalysts measured by ammonia chemisorption method.