Abstract Eleven symmetrically disubstituted 3-acetyl-1, 3-diphenyltriazenes have been synthetized by anew method. The solvolysis kinetics of the title compounds has been measured in 20% aqueous ethanol at several temperatures. The results are discussed from the point of view of temperature and substituent effects on the solvolysis rate constant of the 3-acetyl-1, 3-diphenyltriazenes and conclusions are drawn about the reaction mechanism.