On the basis of the experimental results, the behavior of the alkylation of 2,4,6‐tribromophenol in an alkaline solution of KOH/ organic solvent by phase transfer catalysis is described by a simplified kinetic model. This is due to a measured constant concentration of tetrabutylammonium 2,4,6‐tribromophenoxide (activecatalyst, ArOQ) during the reaction leads to the use of a pseudo‐steady‐state hypothesis in conjunction with the system parameters to build up the simplified kinetic model. The results of the model's prediction are very consistent with the experimental data which are obtained from the two‐phase phase transfer catalytic reaction. The mass transfer resistance of tetrabutylammonium 2,4,6‐tribromophenoxide from the aqueous phase to the organic phase, as well as the mass transfer resistance of tetrabutylammonium bromide from the organic phase to the aqueous phase is negligible. The step of the reaction in the organic phase will also be the rate‐determining step for the whole reaction system. The intrinsic reaction rate constant in the organic phase which is obtained from the organic phase reaction is almost equal to the value obtained in the two‐phase reaction.