The kinetics of the non-catalytic esterification of mono-2-ethylhexyl phthalate has been investigated in an isothermal semibatch reactor. The reaction appears to be second order with respect only to mono-2-ethylhexyl phthalate and the reaction rate does not depend on the concentration of 2-ethylhexanol. The kinetic parameters have been determined. Final comparison of the esterification process in the presence of acid catalysts, amphoteric catalyst and for the non-catalytic reaction has been carried out.