The paper presents an explicit equation for the enhancement factor of a fast irreversible second-order reaction. The equation makes it possible to determine the effective interfacial area and the liquid-phase mass-transfer coefficient of this reaction regime. With the help of a new plot as described in this paper, the Danckwerts plot, and the method for determining the interfacial area by means of a pseudo-first-order reaction the paper discusses a novel method for characterizing the reaction regime of experimental data.