The mechanisms by which highly reactive epoxides hydrolyze in aqueous media are often complex, and can vary as a function of the pH of the solution. The pH-rate profile for the hydrolysis of a given epoxide provides essential information for determining the mechanisms by which the hydrolyses occur. Many of the kinetic studies, however, have been carried out by determining the rates of epoxide hydrolysis in aqueous solutions held at constant ionic strength by addition of electrolytes such as potassium chloride. We have recently shown that potassium chloride induces specific effects in the hydrolysis of indene oxide and a K-region arene oxide, phenanthrene 9,10-oxide. The objective of this report is to study the hydrolysis reactions of several highly reactive epoxides (1,3-cyclopentadiene oxide and 1,3-cyclohexadiene oxide), and also initiate studies on the hydrolysis of several epoxydiol metabolites of the carcinogen benzo(a)pyrene. pH-Rate profiles for the hydrolyses of these compounds will be generated in solutions held at constant ionic strength by potassium chloride and by other less-nucleophilic salts in order to test for the presence of specific salt effects. Such effects could lead to erroneous assignments of hydrolysis mechanisms if not taken into consideration.