The use of the decomposition reaction of cumene hydroperoxide for indication of the end-point of the titration of organic bases with perchloric acid was investigated. The rise in temperature at the end-point is of the order of 25°C. Only strong bases can be determined when the titrand solvent is acetic acid - acetic anhydride (92 + 8 v/v), but even weak bases such as caffeine can be determined in 1,2-dichloroethane. Some titration curves resulting from titration of bases with boron trifluoride (a Lewis acid) are presented.1156761763