Granular activated carbon (GAC) was used as adsorbent in batch experiments for the removal of COD from Purified Terephthalic Acid (PTA) wastewater. The results showed that COD adsorption onto GAC follows pseudo-second-order rate kinetics and that both boundary-layer diffusion and intraparticle diffusion are likely involved in the rate-limiting mechanisms. The adsorption of PTA wastewater components (COD) onto GAC was found to be exothermic. H degrees value is -18.34 kJ/ mol indicating the complexity of the adsorption which is neither completely physical nor chemical in nature. The energetically heterogenic nature of the GAC surface was depicted by the variation in H-st,H-a with the surface loading.