Semibatch reactors (SBRs) are commonly used in the fine and pharmaceutical industries. To prevent thermal runaway incidents in SBRs, the values of maximum temperature of synthesis reaction under adiabatic conditions (MTSR) are expected to be as low as possible. In this work, we experimentally and theoretically demonstrate that MTSR vs reaction temperature(T) profiles tend to present an "S" shape for highly exothermic diffusion controlled liquid-liquid reactions. In other words, the values of MTSR may decrease with T increasing in a certain temperature range. To develop the theoretical criterion to check whether MTSR will increase with T increasing, the quantitative relationship between the maximum accumulation (X-ac(,)max) and nu(A)DaRE kappa(1/2) is developed first. Then the theoretical criterion is developed based on the fact that the first-order derivative of MTSR is equivalent to zero at the optimal reaction temperature. To validate the theoretical criterion, two simulation cases and the reaction of toluene mononitration are conducted.