An apparatus is described for the measurement of the kinetics of fairly fast (half times 1–5 min), homogeneous, liquid chemical reactions, by recording the temperature‐time curve in an adiabatic batch reactor. Adiabatic conditions are maintained by keeping the metal reactor as closely as possible at the same temperature as the reacting species by passing a heating current directly through the walls. Allowance is made for controller set point changes which accompany a temperature increase of the system. Specific heat determinations were carried out on water to test the ability of the control system to maintain adiabatic conditions. The operation of the apparatus is illustrated with kinetic measurements of the hydrolysis of acetic anhydride in dilute aqueous solutions.