Hydrolysis of dimethyl terephthalate (DMT) to produce terephthalic acid (TPA) was studied using a batch reactor. Zink acetate was used as a catalyst to promote the reaction rate. We found that the reaction consists of two reactions: from DMT to mono methyl terephthalate (MMT) and then MMT to TPA. The first reaction is relatively fast and irreversible while the second reaction is relatively slow and reversible. A kinetic equilibrium constant for the second reaction decreases with reaction temperature. A kinetic model consisting of the two reactions for the hydrolysis fitted well with the experimental data.