The interfacial hydrolysis of trimesolyl chloride (TMC) is studied in this work. TMC, together with meta-phenylene diamine (mPDA), forms the pair of monomers commercially used extensively in the preparation of thin film composite membranes for reverse osmosis. The interfacial hydrolysis of TMC is a side reaction in this process, and affects the kinetics of film formation and properties of the film that forms. Here, we develop a methodology for the kinetic study of this hydrolysis, and use it to determine and model the kinetics of hydrolysis of TMC. In order to provide the context, we first establish the circumstances under which it can be competitive with the main reaction. It is shown that pH has a significant effect on the kinetics of hydrolysis, and because of this, the hydrolysis can be self-limiting under most circumstances. The presence of a surfactant, often present in such systems, can influence the kinetics in significant ways. The kinetics has been modeled as a function of the reactant concentration and pH, and the model tested against experimental data obtained with different initial TMC concentrations, and at different concentrations of a commonly used surfactant, Tween 85. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.