Kinetic study on the hydrolysis of diphenylbromomethane does not provide clear-cut evidence for the mechanism of the reaction. The reduction in the rate of the reaction by added bromide ions suggested that the reaction took place by a S[subscript N]1 mechanism. A more detailed study of this common-ion effect, using conductivity to measure the rate of the reaction is described and gives stronger support to this mechanism. (Contains 2 tables.)