Abstract: Phosphate ester hydrolysis plays a very important role in many biological processes. The present investigation belongs to study of kinetic behavior of acid catalyzed hydrolysis of mono-6-chloro-2, 4-dinitroaniline phosphate in 0.1-7.0 mol dm-3 HCl at 50oC in aqueous medium. The log rate profile shows that the rate of reaction increases up to 4.0 mol dm-3 HCl. The results show that mono-6-chloro-2, 4-dinitroaniline phosphate is reactive mainly via conjugated acid species. Positive salt effect has been exhibited through ionic strength data. Behavior of molecularity and order of reaction have been estimated by the use of different concepts and hypothesis, such as Hammett acidity function, Zucker-Hammett hypothesis, Bunnett, Bunett-Olsen and Arrhenius parameters. Isokinetic relationship has been applied to propose probable reaction mechanism for the hydrolysis. Experimental rate coefficients have been found to agree well with theoretical rates in the entire acid range.