The kinetics of the esterification between benzoic acid and isoamyl alcohol has been studied using p-toluenesulphonic acid as a catalyst. The conversion of the benzoic acid was determined by following the concentration of water measured with a Karl Fischer titrator. The effects of the reaction temperature, catalyst concentration, and initial acid to alcohol molar ratio on reaction kinetics have been examined. A five-step assumption was proposed to describe the reaction mechanism for the formation of isoamyl benzoate. And the kinetic model derived from the proposed mechanism can fit well with experimental kinetic data of the esterification, which indicates that the proposed mechanism is reasonable. The nonideality of the liquid reaction mixture has been considered and the activity coefficients of all components were estimated by the UNIFAC model. The reaction rate constants from 353.15K to 383.15K have been determined through the least square method. Meanwhile the activation energy and the standard enthalpy change of reaction in the presence of p-toluenesulphonic acid were calculated to be 50.45kJ/mol and -3.75kJ/mol respectively.