The effect of solvents on ρ values of the Hammett equation which characterizes the hydrolysis of Benzylidene Benzoylhydrazone (BBH) and its derivatives (m—NO2 m—CH3, m—OCH3 and m—Cl), have been studied with four solvents (MeOH, Et0H (1), n—BuOH, and DMSO) by U.V. — spectrophotometry. The effects of solvents on ρ values, one of the Hammett equation parameters, have been reported and discussed.