Methyl p-methyl-t-benzoate was hydrolyzed in basic aqueous alcoholic solution and in 99 to 100% sulfuric acid. The tritium-labeled compound reacts slower than the ordinary compound in the basic solution but at the same rate as the ordinary compound in 99 to 100% sulfuric acid. These differences are explained on the basis of greater electron release of the tritium atom through the inductive effect and smaller electron release by the tritium atom through the electrometric effect. (auth)