Based on on-line pH measurement, a comparative study between batch and semibatch reactors performance has been carried out in a glass-jacketed reactor of 51 provided with the measuring, data acquiring and controlling system. The reaction system chosen was an acid-base reaction, the concentrations of the species in the reactor were obtained simply by measuring the pH of reaction solution. Based on the conductivity profiles of the solution at different temperatures, the kinetic equation of this acid-base reaction was established. The thermal behaviors of batch reactor were investigated by heating and cooling water in the reactor. The dynamic behavior of batch reaction could be described by a set of differential equations resulting from the mass and energy balance of the reaction mixture, the energy balance of the jacket wall and the circulating fluid inside the jacket. This model has been validated with experimental results, and could be applied to the complex control situations.