||The acetovanillone degradation, a toxic by-product of lignin present in cork and paper wastewaters, was studied using gamma radiation as an advanced oxidation process. The main by-products were identified and a tentative mechanism was proposed. Results showed that solution concentrations affected the radiolytic response including the by-products formed. At higher applied dose (50 kGy), acetovanillone was still observed in solutions of high initial concentration while, for low concentration, 20 kGy was enough to completely degrade this compound. Furthermore, at high concentration the predominantly reaction pathways led to structural changes in the benzene ring. At low concentration, the dominate reactions involved breaking of the benzene ring. These promising results demonstrated that gamma radiation can be used for an effective degradation of acetovanillone and provided better insight into the reaction mechanisms for other recalcitrant compounds.